For problem statement at 2000-2999/2000-2099/2080-2089/2085/problemB.txt this is a correct solution, but verifier at 2000-2999/2000-2099/2080-2089/2085/verifierB.go ends with All 120 tests passed. 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 t int
	fmt.Fscan(reader, &t)

	for tc := 0; tc < t; tc++ {
		var n int
		fmt.Fscan(reader, &n)

		a := make([]int, n)
		z := 0
		for i := 0; i < n; i++ {
			fmt.Fscan(reader, &a[i])
			if a[i] == 0 {
				z++
			}
		}

		type Op struct{ l, r int }
		ops := make([]Op, 0, n)

		for z > 0 {
			idx := -1
			for i := 0; i < len(a)-1; i++ {
				if a[i] == 0 && a[i+1] == 0 {
					idx = i
					break
				}
			}
			if idx == -1 {
				for i := 0; i < len(a)-1; i++ {
					if (a[i] == 0 && a[i+1] != 0) || (a[i] != 0 && a[i+1] == 0) {
						idx = i
						break
					}
				}
			}

			mex := 1
			if a[idx] == 0 && a[idx+1] == 1 {
				mex = 2
			} else if a[idx] == 1 && a[idx+1] == 0 {
				mex = 2
			}

			ops = append(ops, Op{idx + 1, idx + 2})

			if a[idx] == 0 {
				z--
			}
			if a[idx+1] == 0 {
				z--
			}

			a[idx] = mex
			a = append(a[:idx+1], a[idx+2:]...)
		}

		if len(a) > 1 {
			ops = append(ops, Op{1, len(a)})
		}

		fmt.Fprintln(writer, len(ops))
		for _, op := range ops {
			fmt.Fprintln(writer, op.l, op.r)
		}
	}
}