For problem statement at 0-999/800-899/870-879/870/problemD.txt this is a correct solution, but verifier at 0-999/800-899/870-879/870/verifierD.go ends with All tests passed can you fix the verifier? package main

import (
	"fmt"
)

func main() {
	var n int
	fmt.Scan(&n)

	A := make([]int, n)
	for i := 0; i < n; i++ {
		fmt.Printf("? %d 0\n", i)
		fmt.Scan(&A[i])
	}

	B := make([]int, n)
	B[0] = A[0]
	for j := 1; j < n; j++ {
		fmt.Printf("? 0 %d\n", j)
		fmt.Scan(&B[j])
	}

	var validP []int
	count := 0

	for p0 := 0; p0 < n; p0++ {
		b0 := p0 ^ A[0]
		p := make([]int, n)
		seen := make([]bool, n)
		possible := true

		for i := 0; i < n; i++ {
			p[i] = A[i] ^ b0
			if p[i] >= n || p[i] < 0 || seen[p[i]] {
				possible = false
				break
			}
			seen[p[i]] = true
		}

		if !possible {
			continue
		}

		b := make([]int, n)
		for i := 0; i < n; i++ {
			b[p[i]] = i
		}

		for j := 0; j < n; j++ {
			if b[j] != B[j]^p0 {
				possible = false
				break
			}
		}

		if possible {
			count++
			if count == 1 {
				validP = p
			}
		}
	}

	fmt.Println("!")
	fmt.Println(count)
	for i := 0; i < n; i++ {
		if i > 0 {
			fmt.Print(" ")
		}
		fmt.Print(validP[i])
	}
	fmt.Println()
}