#include<iostream>
using namespace std;
const int N = 1e5+10;
int T;
int main()
{
cin>>T;
while(T--)
{
int n;
scanf("%d",&n);
if(n%2==0) cout<<(int)(n/2)-1<<endl;
else cout<<(int)(n/2)<<endl;
}
return 0;
}