#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> PII;
const ll mx = 3e5+10;

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int t;
    cin>>t;
    while(t--) {
        ll n;
        cin >> n;

        if(n&1) {
            cout<<n/2<<endl;
        }
        else{
            ll half = n/2;

            cout<<half-1<<endl;
        }
    }
}