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