#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int n;
  cin >> n;
  vector<int> a(n);
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  for (int i = 0; i < n; i++) {
    if (a[i] % 2 == 0) {
      cout << (a[i] / 2) - 1 << endl;
    } else {
      cout << (a[i] - 1) / 2 << endl;
    }
  }
  return 0;
}
