#include<bits/stdc++.h>
using namespace std;
int main()
{
    long long int t,a,b,c,d,e,f,i,j,k,l;
    cin>>t;
    while(t--)
    {
        cin>>a;
        b=a-1;
        cout<<b/2<<endl;
    }

    return 0;
}