For problem statement at 2000-2999/2100-2199/2130-2139/2137/problemF.txt this is a correct solution, but verifier at 2000-2999/2100-2199/2130-2139/2137/verifierF.go ends with candidate runtime error: exit status 2

panic: runtime error: index out of range [-3]

goroutine 1 [running]:
main.(*BIT).Update(...)
	/tmp/cf-worker-2188750638/main.go:17
main.main()
	/tmp/cf-worker-2188750638/main.go:81 +0x4f4 can you fix the verifier? package main

import (
	"io"
	"os"
	"strconv"
	"strings"
)

type BIT struct {
	n   int
	bit []int
}

func (b *BIT) Update(pos, val int) {
	for pos <= b.n {
		if val > b.bit[pos] {
			b.bit[pos] = val
		}
		pos += pos & -pos
	}
}

func (b *BIT) Query(pos int) int {
	res := 0
	for pos > 0 {
		if b.bit[pos] > res {
			res = b.bit[pos]
		}
		pos -= pos & -pos
	}
	return res
}

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

	t := nextInt()
	var out strings.Builder

	for ; t > 0; t-- {
		n := nextInt()
		a := make([]int, n+1)
		b := make([]int, n+1)

		for i := 1; i <= n; i++ {
			a[i] = nextInt()
		}
		for i := 1; i <= n; i++ {
			b[i] = nextInt()
		}

		v := 2 * n
		bit := BIT{n: v, bit: make([]int, v+2)}
		var ans int64

		for i := 1; i <= n; i++ {
			h := 0
			if a[i] == b[i] {
				h = i
			} else {
				th := a[i]
				if b[i] > th {
					th = b[i]
				}
				h = bit.Query(v - th + 1)
			}
			ans += int64(h) * int64(n-i+1)
			bit.Update(v-a[i]+1, i)
		}

		out.WriteString(strconv.FormatInt(ans, 10))
		if t > 1 {
			out.WriteByte('\n')
		}
	}

	os.Stdout.Write([]byte(out.String()))
}