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


#define all(x) (x).begin(), (x).end()
#define sz(x) (int) (x).size()
#define int long long
const int mod = 1e9 + 7, INF = 5e9, N = 2e5 + 2;


bool ok(int n, int sum){
    int rc = (n * (n + 1))/2;
   // debug(n, rc);
    if(rc > sum) return false;
    return true;
}


void solve(int cs){
    int n; cin >> n;
    int sum = 0;
    for(int i = 1 ; i <= n ; i++){
         int x; cin >> x;
         sum += x;
    }
    int low = 0, high = INF;
    while(low + 1 < high){
        int mid = (low + high)>>1;
        if(ok(mid, sum)){
            low = mid;
        }
        else high = mid;
    }
    cout<<low + 1<<'\n';
}

//It's now, or never.
signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    int TEST = 1;
    cin >> TEST;

    for (int i = 1; i <= TEST; i++) {
      //  cout << "Case " << i << ":"<<'\n';
        solve(i);
    }
   
    return 0;
}