Xor sum

#include <iostream>
#include <vector>
#include <string>


int main(int argc, char** argv) {
    long long n, q;
    std::cin >> n >> q;

    std::vector<long long> numbers(n, 0);
    std::vector<long long> xor_until_n(n+1, 0);
    for (int i=0; i<n; i++) {
        int m;
        std::cin >> m;
        numbers.at(i) = m;
        
        if (i == 2) {
            xor_until_n.at(i) = numbers.at(i-2) ^ numbers.at(-1);
        } else if (i > 2) {
            xor_until_n.at(i) = xor_until_n.at(i-1) ^ numbers.at(i-1);
        }
    }

    xor_until_n.at(n) = xor_until_n.at(n-1) ^ numbers.at(n-1);


    std::string result;
    for (int i=0; i<q; i++) {
        long long a, b;
        std::cin >> a >> b;

        int r = xor_until_n.at(b) - xor_until_n.at(a);

        result = result + std::to_string(r) + '\n';

    }

    std::cout << result << std::endl;

    return 0;

}

Test 1

Verdict: RUNTIME ERROR

terminate called after throwing an instance of 'std::out_of_range'
  what():  vector::_M_range_check: __n (which is 18446744073709551615) >= this->size() (which is 8)

Test 2

Verdict: RUNTIME ERROR

terminate called after throwing an instance of 'std::out_of_range'
  what():  vector::_M_range_check: __n (which is 18446744073709551615) >= this->size() (which is 200000)