#include <iostream>

#include <cmath>

using namespace std;

int main()

{

double a, b, x, y;

cin >> a >> b >> x;

if (x > 2)

y = pow(a + b, 1 / 3) * pow(sin (x), 2);

else

y = log(abs(x / (a * b)));

cout<<"y="<<sin(y);

}