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

int main() {
  int t;
  cin >> t;
  while (t--){
    ll n, a, mx = 1, S = 0;
    cin >> n;
    for (int i = 0; i < n; i++){
      cin >> a;
      S += a;
    }
    ll l = 0, r = 1e9;
    while (l <= r){
        ll m = (l + r) / 2;
        ll x = (m * (m + 1)) / 2;
        if (x <= S){
            l = m + 1;
            mx = m + 1;
        } else {
            r = m - 1;
        }
    }
    cout << mx << endl;
  }
  return 0;
}