Candies-and-Two-Sisters.cpp

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