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

#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define INF 1000000001

int main() {
  int T;
  cin >> T;
  rep(i, T) {
    int N;
    cin >> N;
    vector<int> A(N), B(N);
    int dif = INF;
    rep(j, N) {
      cin >> A[j];
      if (j > 0)
	dif = min(A[j] - A[j-1], dif);
    }
    if (dif > 0)
      cout << 0 << endl;
    else
      cout << 1 - dif << endl;
  }
  return 0;
}