#include<bits/stdc++.h>
#define fast() ios::sync_with_stdio(false); cin.tie(0);

using namespace std;
#define ll long long int
#define ft first
#define se second

signed main()
{
    ll tc;
    cin>>tc;
    while(tc--){
        ll n;
        cin>>n;
        ll ans=(n-1)/2;
        cout<<ans<<endl;
    }
    return 0;
}