#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;
    double ans = max(i64(0), (n - 2)) * max(i64(0), (m - 2)) * pow(p, 5);
    ans += max(i64(0), n - 2) * min(i64(2), m) * pow(p, 4);
    ans += max(i64(0), m - 2) * min(i64(2), n) * pow(p, 4);
    ans += min(i64(2), m) * min(i64(2), n) * pow(p, 3);
    printf("%.10f\n", ans);
    return 0;
}