// Online C++ compiler to run C++ program online
#include <bits/stdc++.h>
using namespace std;

int main() {
    int t;
    cin>>t;
    while(t--){
        long long count=0;
      long long N;
      cin>>N;
      if(N%2==0){
          cout<<N/2-1<<endl;
      }
      else
      {
          cout<<N/2<<endl;
      }
}
    return 0;
   
}