#include <bits/stdc++.h>
using namespace std;
#define ll long long

int main()
{
    int t;
    cin >> t;
    while(t--){
        ll n;
        cin >> n;
        
       
      if(n % 2 == 0){
          cout << (n/2) - 1 <<'\n';
      }
      else {
          cout << (n/2) << '\n';
      }
    }

    return 0;
}