Xor sum

#include <iostream>
#include <vector>

using namespace std;



int main() {
    int n, q;
    cin >> n >> q;

    vector<int> arr(n);

    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }

    vector<int> prefix(n);
    prefix[0] = arr[0];
    for (int i = 1; i < n; ++i) {
        prefix[i] = prefix[i-1] ^ arr[i];
    }

    for (int i = 0; i < q; ++i) {
        int a, b;
        cin >> a >> b;
        int res = prefix[b];
        if (a > 0) res ^= prefix[a-1];
        cout << res << '\n';
    }
    return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER