#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll n, m;
    cin >> n >> m;
    if(n > m)swap(n, m);
    double p;
    cin >> p;

    double ans = 0;

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

    cout << fixed << setprecision(10) << ans << endl;
    return 0;
}