#include <bits/stdc++.h>
using namespace std;
#define ll long long int
bool pos(ll mid, ll sum){
    ll need = (mid * (mid+1))/2;
    return sum >= need;
}
void solve()
{
    ll n;
    cin >> n;
    vector<ll> v(n);
    ll tot = 0;
    for(auto &x:v){
        cin>>x;
        tot += x;
    }
    ll l = 0, r = 1e9;
    while(l < r){
        ll mid = (l + r + 1)/2;
        if(pos(mid, tot)){
            l = mid;
        }
        else{
            r = mid - 1;
        }
    }
    cout<<l+1<<endl;
}
int main()
{
    int tc = 1, cs = 1;
    cin >> tc;
    while (tc--)
    {
        // cout<<"Case "<<cs<<": ";
        solve();
    }
    return 0;
}