#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main(){
    int t = 10000;
    cin >> t;
    // cout << t << endl;
    while(t--){
        int s;
        cin >> s;
        cout << s / 2 - (s % 2 == 0) << endl;
    }
    return 0;
}