CP 4 (IEEE)

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

long int calc(long int n, long int m,  long int a)
{
    if (n<=2)
    {
        return a;
    }

     long int fn = pow((3 * a), m) * calc(n-1, m, a);
     long int fx = pow((4 * a), m - 1) * calc(n - 3, m, a);

    return fn + fx;
}

int main()
{
    int n;
    cin>>n;
    for (int i = 1; i <= n; i++)
    {
        long int n,m,a;
        cin >> n >> m >> a;
        cout << calc(n,m,a) <<"\n";
    }

    return 0;
}