#include <iostream>
#include <iomanip>
#include <cmath>

using ldouble = long double;
using lint = long long;

void solve() {
    lint n, m;
    ldouble p;
    std::cin >> n >> m >> p;

    if (n > m) std::swap(n, m);

    ldouble ans;
    if (n == 1) {
        if (m == 1) {
            ans = p;
        } else {
            ans = std::pow(p, 2) * 2 + std::pow(p, 3) * (m - 2);
        }
    } else {
        ans = std::pow(p, 3) * 4 +
              std::pow(p, 4) * ((n + m) * 2 - 8) +
              std::pow(p, 5) * (n - 2) * (m - 2);
    }

    std::cout << std::fixed << std::setprecision(10)
              << ans << std::endl;
}

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

    solve();

    return 0;
}