#ifndef LOCAL
#include <bits/stdc++.h>
#define debug(...)
#endif

using namespace std;
#define int long long
#define cinv(v) for (auto &it:v) cin>>it;
#define coutv(v) for (auto &it:v) cout<< it<<' '; cout<<'\n';

const int INF = 2e5 + 5;

void shelby() {
    int n;
    cin >> n;
    vector<int> v(n);
    cinv(v)
    int sum = accumulate(v.begin(), v.end(), 0LL);
    if (find(v.begin(), v.end(), 0) == v.end()) {
        cout << "0\n";
        return;
    }
    auto ok = [&](int x)-> bool {
        return x * (x + 1) / 2 <= sum;
    };
    int l = 0, r = INF, ans;
    while (l <= r) {
        int m = (l + r) / 2;
        if (ok(m)) ans = m, l = m + 1;
        else r = m - 1;
    }
    cout << ans + 1 << '\n';
}

signed main() {
    cin.tie(0)->sync_with_stdio(0);
    int t = 1;
    cin >> t;
    for (int _ = 1; _ <= t; ++_) {
        // cout << "Case " << _ << ": ";
        shelby();
    }
}