For problem statement at 0-999/700-799/700-709/707/problemB.txt this is a correct solution, but verifier at 0-999/700-799/700-709/707/verifierB.go ends with could not build reference solution: exit status 1
exit status 1 can you fix the verifier? package main

import (
	"bufio"
	"fmt"
	"os"
)

type FastScanner struct {
	r *bufio.Reader
}

func NewFastScanner() *FastScanner {
	return &FastScanner{r: bufio.NewReaderSize(os.Stdin, 1<<20)}
}

func (fs *FastScanner) NextInt() int {
	sign, val := 1, 0
	c, _ := fs.r.ReadByte()
	for (c < '0' || c > '9') && c != '-' {
		c, _ = fs.r.ReadByte()
	}
	if c == '-' {
		sign = -1
		c, _ = fs.r.ReadByte()
	}
	for c >= '0' && c <= '9' {
		val = val*10 + int(c-'0')
		c, _ = fs.r.ReadByte()
	}
	_ = fs.r.UnreadByte()
	return sign * val
}

type Edge struct {
	u int
	v int
	w int64
}

func main() {
	in := NewFastScanner()
	out := bufio.NewWriterSize(os.Stdout, 1<<20)
	defer out.Flush()

	n := in.NextInt()
	m := in.NextInt()
	k := in.NextInt()

	edges := make([]Edge, m)
	for i := 0; i < m; i++ {
		u := in.NextInt()
		v := in.NextInt()
		l := in.NextInt()
		edges[i] = Edge{u: u, v: v, w: int64(l)}
	}

	storage := make([]bool, n+1)
	for i := 0; i < k; i++ {
		a := in.NextInt()
		storage[a] = true
	}

	const inf int64 = 1<<62
	ans := inf
	for _, e := range edges {
		if storage[e.u] != storage[e.v] && e.w < ans {
			ans = e.w
		}
	}

	if k == 0 || k == n || ans == inf {
		fmt.Fprintln(out, -1)
	} else {
		fmt.Fprintln(out, ans)
	}
}