#include<bits/stdc++.h>
#define ll long long
#define el '\n'
#define pb push_back
#define fast ios_base::sync_with_stdio(0); cin.tie(nullptr);
using namespace std;


int main() {

    fast;
    ll t=1;
    cin>>t;
    while(t--) {
        ll n;
        cin>>n;
        ll count = (n-1)/2;
        cout<<count<<el;
    }
    return 0;
}