For problem statement at 0-999/400-499/470-479/475/problemE.txt this is a correct solution, but verifier at 0-999/400-499/470-479/475/verifierE.go ends with All tests passed can you fix the verifier? package main

import (
	"bufio"
	"io"
	"os"
	"strconv"
)

type FastScanner struct {
	data []byte
	idx  int
}

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

type Edge struct {
	to int32
	id int32
}

var (
	tree    [][]int
	weights []int
)

func branchDP(u, p int) (int, int64) {
	sum := weights[u]
	var pairs int64
	for _, v := range tree[u] {
		if v == p {
			continue
		}
		s, pr := branchDP(v, u)
		sum += s
		pairs += pr
	}
	pairs += int64(weights[u]) * int64(sum)
	return sum, pairs
}

func shiftOr(bits []uint64, shift int) {
	word := shift >> 6
	bit := uint(shift & 63)
	if bit == 0 {
		for i := len(bits) - 1; i >= word; i-- {
			bits[i] |= bits[i-word]
		}
	} else {
		r := 64 - bit
		for i := len(bits) - 1; i > word; i-- {
			bits[i] |= (bits[i-word] << bit) | (bits[i-word-1] >> r)
		}
		bits[word] |= bits[0] << bit
	}
}

func main() {
	data, _ := io.ReadAll(os.Stdin)
	fs := &FastScanner{data: data}

	n := fs.nextInt()
	m := fs.nextInt()

	eu := make([]int32, m)
	ev := make([]int32, m)
	deg := make([]int, n)

	for i := 0; i < m; i++ {
		u := fs.nextInt() - 1
		v := fs.nextInt() - 1
		eu[i] = int32(u)
		ev[i] = int32(v)
		deg[u]++
		deg[v]++
	}

	adj := make([][]Edge, n)
	for i := 0; i < n; i++ {
		adj[i] = make([]Edge, 0, deg[i])
	}
	for i := 0; i < m; i++ {
		u := int(eu[i])
		v := int(ev[i])
		adj[u] = append(adj[u], Edge{to: int32(v), id: int32(i)})
		adj[v] = append(adj[v], Edge{to: int32(u), id: int32(i)})
	}

	tin := make([]int, n)
	low := make([]int, n)
	vis := make([]bool, n)
	isBridge := make([]bool, m)
	timer := 0

	var dfsBridge func(int, int)
	dfsBridge = func(u, pe int) {
		vis[u] = true
		tin[u] = timer
		low[u] = timer
		timer++
		for _, e := range adj[u] {
			v := int(e.to)
			id := int(e.id)
			if id == pe {
				continue
			}
			if vis[v] {
				if tin[v] < low[u] {
					low[u] = tin[v]
				}
			} else {
				dfsBridge(v, id)
				if low[v] < low[u] {
					low[u] = low[v]
				}
				if low[v] > tin[u] {
					isBridge[id] = true
				}
			}
		}
	}

	dfsBridge(0, -1)

	comp := make([]int, n)
	for i := 0; i < n; i++ {
		comp[i] = -1
	}

	var compWeights []int
	stack := make([]int, 0, n)

	for i := 0; i < n; i++ {
		if comp[i] != -1 {
			continue
		}
		id := len(compWeights)
		comp[i] = id
		stack = stack[:0]
		stack = append(stack, i)
		cnt := 0
		for len(stack) > 0 {
			u := stack[len(stack)-1]
			stack = stack[:len(stack)-1]
			cnt++
			for _, e := range adj[u] {
				if isBridge[e.id] {
					continue
				}
				v := int(e.to)
				if comp[v] == -1 {
					comp[v] = id
					stack = append(stack, v)
				}
			}
		}
		compWeights = append(compWeights, cnt)
	}

	k := len(compWeights)
	tree = make([][]int, k)
	weights = make([]int, k)
	copy(weights, compWeights)

	for i := 0; i < m; i++ {
		if !isBridge[i] {
			continue
		}
		a := comp[int(eu[i])]
		b := comp[int(ev[i])]
		tree[a] = append(tree[a], b)
		tree[b] = append(tree[b], a)
	}

	totalW := n
	bitsLen := (totalW >> 6) + 1
	var ans int64

	for r := 0; r < k; r++ {
		bits := make([]uint64, bitsLen)
		bits[0] = 1
		var base int64
		sideSum := 0

		for _, nb := range tree[r] {
			s, p := branchDP(nb, r)
			sideSum += s
			base += p
			shiftOr(bits, s)
		}

		best := int64(0)
		maxX := totalW - weights[r]
		for x := 0; x <= maxX; x++ {
			if ((bits[x>>6] >> uint(x&63)) & 1) == 0 {
				continue
			}
			val := int64(weights[r]+x) * int64(totalW-x)
			if val > best {
				best = val
			}
		}

		cur := base + best
		if cur > ans {
			ans = cur
		}
	}

	out := bufio.NewWriterSize(os.Stdout, 1<<20)
	out.WriteString(strconv.FormatInt(ans, 10))
	out.WriteByte('\n')
	out.Flush()
}