#include <cstdio>
#include <iostream>
#include <string>
#include <sstream>
#include <stack>
#include <algorithm>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <cstdlib>
#include <bitset>
#include <tuple>
#include <assert.h>
#include <deque>
#include <bitset>
#include <iomanip>
#include <limits>
#include <chrono>
#include <random>
#include <array>
#include <unordered_map>
#include <functional>
#include <complex>

template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; }

const long long MAX = 5100000;
const long long INF = 1LL << 60;
const long long mod = 1000000007LL;
//const long long mod = 998244353LL;

using namespace std;
typedef unsigned long long ull;
typedef long long ll;



int main()
{
	/*
	cin.tie(nullptr);
	ios::sync_with_stdio(false);
	*/

	ll N, M; scanf("%lld %lld", &N, &M);
	if (N > M) swap(N, M);
	long double P; cin >> P;
	cout << fixed << setprecision(12);
	if (N == 1 && M == 1) {
		cout << P << endl;
	}
	else if (N == 1) {
		long double res = 0;
		res += P * P * 2;
		res += (M - 2) * P * P * P;
		cout << res << endl;
	}
	else {
		long double res = 0;
		res += powl(P, 5) * (M - 2) * (N - 2);
		res += powl(P, 3) * 4;
		res += powl(P, 4) * (N + M - 4) * 2;
		cout << res << endl;
	}
	return 0;
}