#include <bits/stdc++.h>
using namespace std;
int main()
{
    int t;
    cin>>t;
    while(t--){
        long long n;
        cin>>n;
        if(n%2!=0){cout<<floor(n/2.0)<<endl;}
        else{cout<<floor(n/2.0)-1<<endl;}

    }
	
}