Xor sum

input/code.cpp: In function 'int main()':
input/code.cpp:11:19: warning: comparison of integer expressions of different signedness: 'int' and 'ull' {aka 'long long unsigned int'} [-Wsign-compare]
   11 |     for(int i=0; i<n; i++){
      |                  ~^~

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

typedef unsigned long long ull;

int main(){
    ull n, q;
    std::cin >> n >> q;
    vector<ull> xs;
    xs.reserve(n);
    for(int i=0; i<n; i++){
        ull x;
        cin >> x;
        xs.push_back(x);
    }

    for(ull i=0; i<q; i++){
        ull a, b;
        cin >> a >> b;
        ull sum = 0;
        for(ull j=a-1; j<=b-1; j++){
            sum ^= xs[j];
        }
        cout << sum << endl;
    }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: TIME LIMIT EXCEEDED