#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    long long number;
    cin >> number;
    if (number == 2) {
      cout << 0 << endl;
    } else if (number == 1) {
      cout << 0 << endl;
    } else {
      if (number % 2 == 0) {
        cout << number / 2 - 1 << endl;
      } else {
        cout << number / 2 << endl;
      }
    }
  }
  return 0;
}
