Help me in solving MAXIMALEXP problem

help
,
1

My issue

Why am I wrong here ?

My code

#include <iostream>
using namespace std;

int main() {
	int t;
	cin >> t;
	while(t--)
	{
	    long long int n;
	    long long int k;
	    cin >> n >> k;
	    if(n < 2*k - 1)
	    {
	        cout << n/2 << endl;
	    }
	    else if(n == 2*k - 1)
	    {
	        cout << (k-1)/2;
	    }
	    else
	    {
	        long long int x1 = n % k;
	        if(x1 == k-1)
	        {
	            cout << x1/2 << endl;;
	        }
	        else
	        {
	            x1 += k;
	            cout << x1/2 << endl;
	        }
	    }
	}
	return 0;
}

Problem Link: MAXIMALEXP Problem - CodeChef