For problem statement at 1000-1999/1600-1699/1680-1689/1682/problemE.txt this is a correct solution, but verifier at 1000-1999/1600-1699/1680-1689/1682/verifierE.go ends with case 3 failed: expected "1\n2" got "1 2"
input:
4 2
4 3 2 1
1 4
2 3 can you fix the verifier? ```go
package main

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

type Edge struct {
	to int
	id int
}

type Item struct {
	kind int
	x    int
}

func main() {
	data, _ := io.ReadAll(os.Stdin)
	idx := 0
	nextInt := func() int {
		for idx < len(data) && (data[idx] < '0' || data[idx] > '9') {
			idx++
		}
		val := 0
		for idx < len(data) && data[idx] >= '0' && data[idx] <= '9' {
			val = val*10 + int(data[idx]-'0')
			idx++
		}
		return val
	}

	n := nextInt()
	m := nextInt()

	p := make([]int, n+1)
	for i := 1; i <= n; i++ {
		p[i] = nextInt()
	}

	vis := make([]bool, n+1)
	pos := make([]int, n+1)
	cycles := make([][]int, 0)

	for i := 1; i <= n; i++ {
		if vis[i] {
			continue
		}
		cur := i
		cyc := make([]int, 0)
		for !vis[cur] {
			vis[cur] = true
			pos[cur] = len(cyc)
			cyc = append(cyc, cur)
			cur = p[cur]
		}
		cycles = append(cycles, cyc)
	}

	adj := make([][]Edge, n+1)
	for i := 1; i <= m; i++ {
		x := nextInt()
		y := nextInt()
		adj[x] = append(adj[x], Edge{y, i})
		adj[y] = append(adj[y], Edge{x, i})
	}

	parent := make([]int, n+1)
	parentEdge := make([]int, n+1)
	minPos := make([]int, n+1)
	maxPos := make([]int, n+1)
	children := make([][]int, n+1)

	ans := make([]int, 0, m)

	for _, cyc := range cycles {
		if len(cyc) <= 1 {
			continue
		}

		root := cyc[0]

		for _, v := range cyc {
			parent[v] = 0
			minPos[v] = pos[v]
			maxPos[v] = pos[v]
			children[v] = children[v][:0]
		}

		order := make([]int, 0, len(cyc))
		st := make([]int, 0, len(cyc))
		st = append(st, root)
		parent[root] = -1

		for len(st) > 0 {
			u := st[len(st)-1]
			st = st[:len(st)-1]
			order = append(order, u)
			for _, e := range adj[u] {
				v := e.to
				if v == parent[u] {
					continue
				}
				parent[v] = u
				parentEdge[v] = e.id
				children[u] = append(children[u], v)
				st = append(st, v)
			}
		}

		for i := len(order) - 1; i >= 0; i-- {
			u := order[i]
			for _, v := range children[u] {
				if minPos[v] < minPos[u] {
					minPos[u] = minPos[v]
				}
				if maxPos[v] > maxPos[u] {
					maxPos[u] = maxPos[v]
				}
			}
		}

		for _, u := range cyc {
			if len(children[u]) > 1 {
				sort.Slice(children[u], func(i, j int) bool {
					return minPos[children[u][i]] < minPos[children[u][j]]
				})
			}
		}

		items := make([]Item, 0, 2*len(cyc))
		items = append(items, Item{0, root})

		for len(items) > 0 {
			it := items[len(items)-1]
			items = items[:len(items)-1]

			if it.kind == 1 {
				ans = append(ans, it.x)
				continue
			}

			u := it.x
			ch := children[u]
			for i := len(ch) - 1; i >= 0; i-- {
				v := ch[i]
				eid := parentEdge[v]
				if pos[v] == maxPos[v] {
					items = append(items, Item{0, v})
					items = append(items, Item{1, eid})
				} else {
					items = append(items, Item{1, eid})
					items = append(items, Item{0, v})
				}
			}
		}
	}

	out := make([]byte, 0, m*7)
	for i, x := range ans {
		if i > 0 {
			out = append(out, ' ')
		}
		out = strconv.AppendInt(out, int64(x), 10)
	}
	out = append(out, '\n')
	os.Stdout.Write(out)
}
```