#include <bits/stdc++.h>   using namespace std;   int n, t;   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> t;     while (t--) {       cin >> n;       if (n <= 2) {         cout << 0 << endl;         continue;       } else {         int x;         x = n / 2;         if (n % 2 == 0) x--;         cout << x << endl;       }     }   }   