#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<<endl;
        }
        else{
            cout<<(n/2)-1<<endl;
        }
    }
}