#include <bits/stdc++.h>

using namespace std;
typedef long long ll;


int main()
{


    ll h, w;
    double p;
    cin >> h >> w;
    cin >> p;
    
    if (h == 1 && w == 1)
        p = p;
    else if (h == 1)
        p = 2 * pow(p, 2) + pow(p, 3) * (w - 2);
    else if (w == 1)
        p = 2 * pow(p, 2) + pow(p, 3) * (h - 2);
    else
        p = 4 * pow(p, 3) + pow(p, 4) * (2*(h + w - 4)) + pow(p, 5) * ( (h-2) * (w-2) );
    printf("%.8f\n" , p);
    

    return 0;
}