#include<bits/stdc++.h>
using namespace std; 
char nl = '\n';
using i64 = long long;

void solve(int t) {
    // cout << "test #" << t << nl;
    i64 n; cin >> n;
    vector<i64> A(n);
    for (auto& a : A) cin >> a;
    i64 sum = accumulate(A.begin(), A.end(), 0LL);
    i64 s = 0, e = 2e9;
    i64 ans = 0;
    while (s <= e) {
        i64 mid = (s + e) >> 1;
        i64 cnt = (mid * (mid + 1)) / 2LL;
        if (cnt <= sum) {
            ans = mid + 1;
            s = mid + 1;
        } else {
            e = mid - 1;
        }
    }
    cout << ans << nl;
} 

int main() {
    int tt = 1;
    cin >> tt;
    for(int t = 1; t <= tt; t++) solve(t);
}