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

int main() {
  long long n, m;
  long double p;
  cin >> n >> m >> p;
  if (n > m) {
	  swap(n, m);
	}
  long double ans;
  if (m == 1) {
	  ans = p;
	}
  else if (n == 1) {
	  ans = 2 * pow(p, 2.0) + (m - 2) * pow(p, 3.0);
	} else {
	  ans = 4 * pow(p, 3.0) + (2 * m + 2 * n - 8) * pow(p, 4.0) + (n - 2) * (m - 2) * pow(p, 5.0);
	}
  cout << setprecision(16) << ans << endl;
  return 0;
}