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

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