#include <bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
    int T;
    cin >> T;
    while (T--) {
        int n;
        cin >> n;
        int ans=0;
        if (n % 2 == 0) {
            ans=  (n/2)- 1;
        } else {
            ans = (n/2);
        }
        cout << ans << endl;
    }
    return 0;
}