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