RXD and math

#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<string.h>
#include<math.h>
using namespace std;
int main()
{
    long long n,k;
    int T=1;
    while(scanf("%lld%lld",&n,&k)!=EOF)
    {
        long long sum=1;
        n=n%1000000007;
        while(k)
        {
            if(k%2==0)
            {
                n=n*n%1000000007;
                k=k/2;
            }
            else
            {
                sum=(sum%1000000007)*(n%1000000007);
                sum=sum%1000000007;
                k--;
            }
        }

        printf("Case #%d: %lld\n",T++,sum);
    }
}