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