A - Candies and Two Sisters.cpp

#include<bits/stdc++.h>
using namespace std;

int main()
{
    long int t;
    cin>>t;
    long long int x;
    while(t--)
    {
        cin>>x;
        if(x==1 || x==2)
            cout<<"0"<<endl;
        else if(x%2==0)
            cout<<x/2-1<<endl;
        else
            cout<<x/2<<endl;
    }
    return 0;
}