#pragma once

#include <bits/stdc++.h>

#define M_PI       3.14159265358979323846   // pi

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> VI;
typedef pair<ll, ll> P;
typedef tuple<ll, ll, ll> t3;
typedef tuple<ll, ll, char, ll> t4;

#define rep(a,n) for(int a = 0;a < n;a++)
#define repi(a,b,n) for(int a = b;a < n;a++)

const ll mod = 1000000007;

bool Compare(t4& left, t4& right) {
	ll a, b, d, e, f,h;
	char c, g;
	tie(a, b, c, d) = left;
	tie(e, f, g, h) = right;
	if (a == e) {
		return d < h;
	}
	return a < e;
}

int main(void)
{
	ll n, m;
	cin >> n >> m;
	double p;
	cin >> p;
	cout << fixed << setprecision(10);
	if (n == 1 && m == 1) {
		cout << p << endl; 
		return 0; 
	}
	else if (n == 1) {
		double r = pow(p, 2) * 2
			+ pow(p, 3) * (m - 2);
		cout << r << endl;
		return 0;
	}
	else if (m == 1) {
		double r = pow(p, 2) * 2
			+ pow(p, 3) * (n - 2);
		cout << r << endl;
		return 0;
	}
	else {
		double r = pow(p, 3) * 4
			+ pow(p, 4) * (n - 2) * 2
			+ pow(p, 4) * (m - 2) * 2;
		r += pow(p, 5) * max(n - 2, 0LL) * max(m - 2, 0LL);
		cout << r << endl;
		return 0;
	}
}