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