#include <bits/stdc++.h>
using namespace std;
#define el "\n"
#define ll long long int
#define loop(n) for (int i = 0; i < n; i++)
void solve()
{
    int t;  cin>>t;
    while(t--){
        int n;
        cin>>n;
        if(n&1)cout<<n/2<<endl;
        else cout<<(n/2)-1<<endl;
    }
}
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    solve();
    return 0;
}