#include<bits/stdc++.h>
using namespace std;
int main(){

	int t;
	cin >> t;

   

	while(t--){
		
		int n;
		cin >> n;
        
		if(n%2==0) cout<<(n/2)-1 << endl;
		else cout << n/2 << endl;
	}
	
	

	
}