#include <bits/stdc++.h>
using namespace std;
int main() {
  int t, i;
  long long int n;
  cin >> t;
  for (i = 0; i < t; i++) {
    cin >> n;
    if (n == 1) {
      cout << "0" << endl;
    } else if (n == 2) {
      cout << "0" << endl;
    } else {
      cout << (n - 1) / 2 << endl;
    }
  }
}
