#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
int main() {
    double N, M, P;
    cin >> N >> M >> P;
    if (N > M) {
        ll t = M;
        M = N;
        N = t;
    }
    if (M == 1) {
        cout << P << "\n";
        return 0;
    }
    if (N == 1) {
        double ans = 2 * P * P;
        ans += pow(P, 3) * max(0.0, M - 2);
        printf("%10.8f\n", ans);
        return 0;
    }
    double ans = 4 * pow(P, 3) + (2 * (N - 2) + 2 * (M - 2)) * pow(P, 4) + (N * M - (2 * N + 2 * (M - 2))) * pow(P, 5);
    printf("%10.8f\n", ans);
    return 0;
}