Xor sum

#include <bits/stdc++.h> 
using namespace std;


int xor_sum(int a,int b){
    int axb =0;
    int count = 0;
    while (a>0 && b>0){
        
        if (a%2 ==1){
            if (b%2 == 0){
                axb += 2^count;
                b /=2;
            }
            else{
                b= (b-1)/2;
            }
            a = (a-1)/2;
        }
        else{
            if (b%2 == 1){
                axb += 2^count;
                b = (b-1)/2;
            }
            else{
                b /=2;
            }
            a = a/2;
        }
        count+=1;
    }
    return axb;
}
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    int n, q;
    cin >> n >> q;
    vector<int> tree(2 * n);
    for (int i = 0; i < n; i++) {
        cin >> tree[n + i];
    }
    for (int i = n-1; i > 0; --i) {
        tree[i] = xor_sum(tree[2 * i],tree[2 * i + 1]);
    }
    for (int i =0; i<q; i++){
        int a;
        int b;
        cin>>a>>b;
        a += n; b += n;
        int s = 0;
        while (a <= b) {
        if (a%2 == 1) s = xor_sum(s,tree[a++]);
        if (b%2 == 0) s = xor_sum(s,tree[b--]);
        a /= 2; b /= 2;
        }
        cout<<s<<"\n";
    }
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER