#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
ll mod=998244353;
ll inva(ll N) {
    ll a = N, b = mod, c = 1, d = 0;
    while (b > 0) {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        c -= t * d;
        swap(c, d);

    }
    c %= mod;
    if (c < 0)c += mod;
    return c;

}//割り算時に使う逆元を求める.


int main() {
    ll N,M;
    cin>>N>>M;
    double P;
    cin>>P;
    if(M<N)swap(N,M);
    cout<<setprecision(16);
    if(M==1){
        cout<<P<<endl;
        return 0;

    }
    if(N==1){
        cout<<2*P*P+(M-2)*P*P*P<<endl;
        return 0;

    }
    cout<<4*P*P*P+2*(N+M-4)*P*P*P*P+(N*M-2*N-2*M+4)*P*P*P*P*P<<endl;
}