For problem statement at 1000-1999/1000-1099/1030-1039/1037/problemG.txt this is a correct solution, but verifier at 1000-1999/1000-1099/1030-1039/1037/verifierG.go ends with panic: exit status 1

goroutine 1 [running]:
main.genCase(0x4000074ee8)
	/home/ubuntu/codeforces/1000-1999/1000-1099/1030-1039/1037/verifierG.go:58 +0x394
main.main()
	/home/ubuntu/codeforces/1000-1999/1000-1099/1030-1039/1037/verifierG.go:76 +0x18c
exit status 2 can you fix the verifier? package main

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

func main() {
	reader := bufio.NewReader(os.Stdin)
	writer := bufio.NewWriter(os.Stdout)
	defer writer.Flush()

	var s string
	fmt.Fscan(reader, &s)

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

	var m int
	fmt.Fscan(reader, &m)

	for i := 0; i < m; i++ {
		var l, r int
		fmt.Fscan(reader, &l, &r)
		
		var compLen int
		if l == r {
			compLen = 1
		} else {
			pairs := pref[r-1] - pref[l-1]
			compLen = (r - l + 1) - pairs
		}

		if compLen%2 == 1 {
			fmt.Fprintln(writer, "Alice")
		} else {
			fmt.Fprintln(writer, "Bob")
		}
	}
}