#include <iostream>
#include <cstdio>
#include <cstring>
#include <vector>
#include <deque>
#include <queue>
#include <array>
#include <set>
#include <map>
#include <cmath>
#include <complex>
#include <algorithm>
#include <numeric>
#include <utility>
#include <tuple>
#include <functional>
#include <bitset>
#include <cstdint>
#include <cassert>
#include <random>

using namespace std;
using i64 = int64_t;
using i32 = int32_t;
template<class T> T iabs(const T& x) { return max(x, -x); }

int main() {
    i64 n, m;
    double p;
    cin >> n >> m >> p;
    if (n > m) swap(n, m);
    double ans;
    if (n == 1) {
        if (m == 1) {
            ans = p;
        } else {
            ans = (m - 2) * pow(p, 3) + 2 * pow(p, 2);
        }
    } else {
        ans = (n - 2) * (m - 2) * pow(p, 5)
            + (2 * (n - 2) + 2 * (m - 2)) * pow(p, 4)
            + 4 * pow(p, 3);
    }
    printf("%.10f\n", ans);
    return 0;
}