For problem statement at 0-999/900-999/980-989/983/problemE.txt this is a correct solution, but verifier at 0-999/900-999/980-989/983/verifierE.go ends with case 1 failed
input:
3
1
1
3 3
1
2 3
expected:
-1
got: can you fix the verifier? package main

import (
	"bytes"
	"io"
	"os"
	"sort"
	"strconv"
)

const LOG = 20
const INF = int(1e9)

type FastScanner struct {
	data []byte
	idx  int
	n    int
}

func NewFastScanner() *FastScanner {
	data, _ := io.ReadAll(os.Stdin)
	return &FastScanner{data: data, n: len(data)}
}

func (fs *FastScanner) NextInt() int {
	for fs.idx < fs.n {
		c := fs.data[fs.idx]
		if c >= '0' && c <= '9' {
			break
		}
		fs.idx++
	}
	val := 0
	for fs.idx < fs.n {
		c := fs.data[fs.idx]
		if c < '0' || c > '9' {
			break
		}
		val = val*10 + int(c-'0')
		fs.idx++
	}
	return val
}

type Dual struct {
	size int
	data []int
}

func NewDual(n int) *Dual {
	size := 1
	for size < n {
		size <<= 1
	}
	data := make([]int, size<<1)
	for i := range data {
		data[i] = INF
	}
	return &Dual{size: size, data: data}
}

func (d *Dual) RangeChMin(l, r, val int) {
	l += d.size - 1
	r += d.size - 1
	for l <= r {
		if l&1 == 1 {
			if val < d.data[l] {
				d.data[l] = val
			}
			l++
		}
		if r&1 == 0 {
			if val < d.data[r] {
				d.data[r] = val
			}
			r--
		}
		l >>= 1
		r >>= 1
	}
}

func (d *Dual) Point(p int) int {
	idx := p + d.size - 1
	res := INF
	for idx > 0 {
		if d.data[idx] < res {
			res = d.data[idx]
		}
		idx >>= 1
	}
	return res
}

type Point struct {
	x int
	y int
}

type Rect struct {
	l1  int
	r1  int
	l2  int
	r2  int
	idx int
}

type Event struct {
	y    int
	l    int
	r    int
	idx  int
	sign int
}

type Pair struct {
	v int
	h int
}

var (
	n         int
	parentUp  [][]int
	parent    []int
	depth     []int
	heavy     []int
	headH     []int
	pos       []int
	tout      []int
	subSize   []int
	busUp     [][]int
	childHead []int
	childTo   []int
	childNext []int
)

func ancestorAtDepth(x, targetDepth int) int {
	diff := depth[x] - targetDepth
	k := 0
	for diff > 0 {
		if diff&1 == 1 {
			x = parentUp[k][x]
		}
		diff >>= 1
		k++
	}
	return x
}

func lca(a, b int) int {
	if depth[a] < depth[b] {
		a, b = b, a
	}
	diff := depth[a] - depth[b]
	k := 0
	for diff > 0 {
		if diff&1 == 1 {
			a = parentUp[k][a]
		}
		diff >>= 1
		k++
	}
	if a == b {
		return a
	}
	for k = LOG - 1; k >= 0; k-- {
		if parentUp[k][a] != parentUp[k][b] {
			a = parentUp[k][a]
			b = parentUp[k][b]
		}
	}
	return parentUp[0][a]
}

func updatePath(a, b, val int, dual *Dual) {
	for headH[a] != headH[b] {
		if depth[headH[a]] < depth[headH[b]] {
			a, b = b, a
		}
		dual.RangeChMin(pos[headH[a]], pos[a], val)
		a = parent[headH[a]]
	}
	if depth[a] > depth[b] {
		a, b = b, a
	}
	dual.RangeChMin(pos[a], pos[b], val)
}

func distToAncestor(x, anc int) (int, int, bool) {
	if x == anc {
		return 0, anc, true
	}
	cur := x
	steps := 0
	for k := LOG - 1; k >= 0; k-- {
		nxt := busUp[k][cur]
		if nxt != 0 && depth[nxt] > depth[anc] {
			cur = nxt
			steps += 1 << k
		}
	}
	nxt := busUp[0][cur]
	if nxt != 0 && depth[nxt] <= depth[anc] {
		return steps + 1, cur, true
	}
	return 0, 0, false
}

func bitAdd(bit []int, idx, val int) {
	for idx <= n {
		bit[idx] += val
		idx += idx & -idx
	}
}

func bitSum(bit []int, idx int) int {
	res := 0
	for idx > 0 {
		res += bit[idx]
		idx -= idx & -idx
	}
	return res
}

func main() {
	fs := NewFastScanner()

	n = fs.NextInt()

	parent = make([]int, n+1)
	depth = make([]int, n+1)
	childHead = make([]int, n+1)
	for i := 1; i <= n; i++ {
		childHead[i] = -1
	}
	childTo = make([]int, n)
	childNext = make([]int, n)

	ec := 0
	for i := 2; i <= n; i++ {
		p := fs.NextInt()
		parent[i] = p
		depth[i] = depth[p] + 1
		childTo[ec] = i
		childNext[ec] = childHead[p]
		childHead[p] = ec
		ec++
	}

	parentUp = make([][]int, LOG)
	parentUp[0] = parent
	for k := 1; k < LOG; k++ {
		parentUp[k] = make([]int, n+1)
		prev := parentUp[k-1]
		cur := parentUp[k]
		for v := 1; v <= n; v++ {
			cur[v] = prev[prev[v]]
		}
	}

	subSize = make([]int, n+1)
	heavy = make([]int, n+1)
	best := make([]int, n+1)
	for i := 1; i <= n; i++ {
		subSize[i] = 1
	}
	for v := n; v >= 2; v-- {
		p := parent[v]
		subSize[p] += subSize[v]
		if subSize[v] > best[p] {
			best[p] = subSize[v]
			heavy[p] = v
		}
	}

	headH = make([]int, n+1)
	pos = make([]int, n+1)
	tout = make([]int, n+1)

	stack := make([]Pair, 0, n)
	stack = append(stack, Pair{1, 1})
	curPos := 1
	for len(stack) > 0 {
		pr := stack[len(stack)-1]
		stack = stack[:len(stack)-1]
		v, h := pr.v, pr.h
		for x := v; x != 0; x = heavy[x] {
			headH[x] = h
			pos[x] = curPos
			curPos++
			for e := childHead[x]; e != -1; e = childNext[e] {
				c := childTo[e]
				if c != heavy[x] {
					stack = append(stack, Pair{c, c})
				}
			}
		}
	}
	for v := 1; v <= n; v++ {
		tout[v] = pos[v] + subSize[v] - 1
	}

	dual := NewDual(n)

	m := fs.NextInt()
	pointsByL := make([][]Point, n+1)

	for i := 0; i < m; i++ {
		a := fs.NextInt()
		b := fs.NextInt()
		l := lca(a, b)
		updatePath(a, b, depth[l], dual)
		if l != a && l != b {
			x, y := pos[a], pos[b]
			if x > y {
				x, y = y, x
			}
			pointsByL[l] = append(pointsByL[l], Point{x, y})
		}
	}

	up1 := make([]int, n+1)
	for v := 1; v <= n; v++ {
		md := dual.Point(pos[v])
		if md < depth[v] {
			up1[v] = ancestorAtDepth(v, md)
		}
	}

	busUp = make([][]int, LOG)
	busUp[0] = up1
	for k := 1; k < LOG; k++ {
		busUp[k] = make([]int, n+1)
		prev := busUp[k-1]
		cur := busUp[k]
		for v := 1; v <= n; v++ {
			cur[v] = prev[prev[v]]
		}
	}

	q := fs.NextInt()
	ans := make([]int, q)
	rectByL := make([][]Rect, n+1)

	for i := 0; i < q; i++ {
		v := fs.NextInt()
		u := fs.NextInt()
		l := lca(v, u)

		if l == v {
			d, _, ok := distToAncestor(u, l)
			if ok {
				ans[i] = d
			} else {
				ans[i] = -1
			}
			continue
		}
		if l == u {
			d, _, ok := distToAncestor(v, l)
			if ok {
				ans[i] = d
			} else {
				ans[i] = -1
			}
			continue
		}

		dv, pv, ok1 := distToAncestor(v, l)
		du, pu, ok2 := distToAncestor(u, l)
		if !ok1 || !ok2 {
			ans[i] = -1
			continue
		}

		ans[i] = dv + du
		l1, r1 := pos[pv], tout[pv]
		l2, r2 := pos[pu], tout[pu]
		if l1 > l2 {
			l1, l2 = l2, l1
			r1, r2 = r2, r1
		}
		rectByL[l] = append(rectByL[l], Rect{l1, r1, l2, r2, i})
	}

	bit := make([]int, n+2)

	for l := 1; l <= n; l++ {
		rects := rectByL[l]
		if len(rects) == 0 {
			continue
		}
		pts := pointsByL[l]
		if len(pts) == 0 {
			continue
		}

		sort.Slice(pts, func(i, j int) bool {
			return pts[i].y < pts[j].y
		})

		events := make([]Event, 0, len(rects)*2)
		for i, r := range rects {
			events = append(events, Event{r.r2, r.l1, r.r1, i, 1})
			events = append(events, Event{r.l2 - 1, r.l1, r.r1, i, -1})
		}
		sort.Slice(events, func(i, j int) bool {
			return events[i].y < events[j].y
		})

		cnt := make([]int, len(rects))
		pi := 0
		for _, e := range events {
			for pi < len(pts) && pts[pi].y <= e.y {
				bitAdd(bit, pts[pi].x, 1)
				pi++
			}
			cnt[e.idx] += e.sign * (bitSum(bit, e.r) - bitSum(bit, e.l-1))
		}

		for i, r := range rects {
			if cnt[i] > 0 {
				ans[r.idx]--
			}
		}

		for i := 0; i < pi; i++ {
			bitAdd(bit, pts[i].x, -1)
		}
	}

	var out bytes.Buffer
	for i := 0; i < q; i++ {
		out.WriteString(strconv.Itoa(ans[i]))
		out.WriteByte('\n')
	}
	_, _ = os.Stdout.Write(out.Bytes())
}