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#include <bits/stdc++.h>
#define all(x) (x).begin(),(x).end()
using namespace std;

using ll = long long;
using ld = long double;

#define int ll
#define sz(x) ((int)(x).size())

using pii = pair<int,int>;
using tii = tuple<int,int,int>;

void testcase() {
   int n;
   cin >> n;
   vector<int> v(n);
   for(auto &x : v) cin >> x;
   
   auto f = [](int a, int b, int c) {
      if(b >= 1e4) return (int)1e9;
      return b * (b - 1) * (b - 2) / 6 + b * (b - 1) / 2 * (a + c) + a * b * c;
   };
   auto find = [&](int L, int S, int lim) {
      int l = -1;
      for(int i = 30; i >= 0; i--) {
         if(l + (1 << i) > S) continue;
         if(f(L, l + (1 << i), S - (l + (1 << i))) < lim) l += (1 << i);
      }
      return l + 1;
   };
   
   int l = -1;
   for(int i = 30; i >= 0; i--) {
      const int S = l + (1 << i);
      int sweep = S;
      bool ok = 1;
      for(auto x: v) {
         int now = find(S - sweep, sweep, x);
         if(now > sweep) { ok = 0; break; }
         sweep -= now;
      }
      if(!ok) l = S;
   }
   
   cout << l + 1 << '\n';
}

signed main() {
   cin.tie(0) -> sync_with_stdio(0);
   int T;
   cin >> T;
   while(T--) testcase();
}

/**
      Binecuvanteaza Doamne Ukraina.
--
*/