#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define endl '\n'
#define ll long long
#define ld long double
#define vi vector<ll>
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define srt(v) sort(v.begin(),v.end())
#define rsrt(v) sort(v.rbegin(),v.rend())
#define rep(i, a, b) for(ll i = (a); i < (b); i++)
#define trace(x) cout<<#x<<": "<<x<<endl;
#define print(v) for(auto e:v) cout<<e<<" "; cout<<endl;
#define printp(v) for(auto e:v) cout<<e.first<<" "<<e.second<<endl;
const ll N=1e6+10;

ll is_ok(ll mid,ll sum){
    ll ki = mid*(mid+1);
    ki/=2;
    return ki;
}
void solve() {
    ll n;cin>>n;
    vi p(n);
    ll sum =0;
    map<ll,ll>mpp;
    rep(i,0,n){
        cin>>p[i];
        sum += p[i];
        mpp[1]+=p[i];
    }
    ll l = 0,h = 1e9;
    ll ans = -1;
    while (l<=h)
    {
        ll mid = (l+h)>>1;
        ll ki = is_ok(mid,sum);
        if(ki==sum){
            ans = mid;
            break;
        }
        else if(ki>sum){
            h = mid-1;
        }
        else{
            l = mid+1;
        }
    }
    cout<<ans+1<<endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    int t=1;cin>>t;
    for(int i =1;i<=t;i++){
        solve();
    }
    return 0;
}