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