Missing Coin Sum

input/code.cpp: In function 'int main()':
input/code.cpp:24:19: warning: comparison of integer expressions of different signedness: 'int' and 'ull' {aka 'long long unsigned int'} [-Wsign-compare]
   24 |     for(int i=0; i<n; i++){
      |                  ~^~

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);

    ull n;
    cin >> n;

    vector<ll> as;
    as.reserve(n);
    for(ull i=0; i<n; i++){
        ll a;
        cin >> a;
        as.push_back(a);
    }

    sort(as.begin(), as.end());

    ll s = 0;
    for(int i=0; i<n; i++){
        if(as[i] > s+1){
            break;
        }
        s+= as[i];
    }
    cout << (s+1) << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED