#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    double x,y,z,t;
    cin>>x>>y>>z;
    t=(x*y*z-y*abs(x+sqrt(z)))/(pow(10.0,7.0)+pow(log10(4.0),4.0));
    cout<<t;
    return 0;
}