2017. H (WA)

#include <iostream>
#include <string>
#include <cmath>

using namespace std;

double k =0;
unsigned long long x,y,z;
unsigned long long n;

unsigned long long solve()
{

  //  x[m] = y^(m-1) * x[1] + z * (y^(m-1) - 1) / (y - 1) mod 20000
     unsigned long long temp = pow(y, n-1) * x +(z*(pow(y,n-1)-1)/(y-1));
    if(temp>20000)
        temp = temp%20000;

    return temp;
}

int main()
{

int tests =0;
cin >> tests;
cin.ignore();
 while(tests--)
    {
    scanf("%Ld %Ld %Ld %Ld", &x, &y, &z, &n);
    unsigned long long result = solve();
    cout << result;
    }
return 0;

}