#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <iterator>
#include <limits>
#include <list>
#include <locale>
#include <map>
#include <memory>
#include <new>
#include <numeric>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <typeinfo>
#include <utility>
#include <valarray>
#include <vector>
#include <climits>
#include <cstring>
#include <cassert>

using namespace std;
using Int = long long int;

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    Int N, M;
    double P;
    cin >> N >> M >> P;
    assert(1 <= N && N <= 1000000000);
    assert(1 <= M && M <= 1000000000);
    assert(0.0 <= P && P <= 1.0);

    if (N == 1 && M == 1) {
        cout << P << endl;
        return 0;
    }

    if (N > M) swap(N, M);
    if (N == 1) {
        double ans = (M - 2) * pow(P, 3) + 2 * pow(P, 2);
        cout << ans << endl;
        return 0;
    }

    Int cnt_corner = 4;
    Int cnt_outer = max(0ll, N - 2) * 2 + max(0ll, M - 2) * 2;
    Int cnt_inner = N * M - cnt_corner - cnt_outer;

    double p_corner = pow(P, 3);
    double p_outer = pow(P, 4);
    double p_inner = pow(P, 5);

    double ans = cnt_corner * p_corner + cnt_outer * p_outer + cnt_inner * p_inner;
    cout << ans << endl;

    return 0;
}