#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int t;
  cin >> t;
  while(t--) {
    int n;
    cin >> n;
    cout << ceil((double)n/2-1)<<"\n";
  }
}