#include <stdio.h>
#include <string>
#include <cstring>
#include <stdlib.h>
#include <math.h>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <list>
#include <iterator>
#include <assert.h>
#pragma warning(disable:4996) 
 
typedef long long ll;
#define MIN(a, b) ((a)>(b)? (b): (a))
#define MAX(a, b) ((a)<(b)? (b): (a))
#define LINF 9223300000000000000
#define INF 2140000000
const long long MOD = 1000000007;
//const long long MOD = 998244353;
using namespace std;
 



int main(int argc, char* argv[])
{
    int n,m;
    scanf("%d%d", &n, &m);
    double p;
    scanf("%lf", &p);

    double pp[10];
    pp[0]=1;
    int i;
    for(i=0; i<9; i++) {
        pp[i+1]=pp[i]*p;
    }

    if(n>m) swap(n,m);
    if(n==1) {
        if(m==1) {
            printf("%.10e\n", p); return 0;
        }
        double ans=2*pp[2]+(m-2)*pp[3];
        printf("%.10e\n", ans);
    }
    else {
        double ans=4*pp[3]+((double)n*2-4+(double)m*2-4)*pp[4]+(double)(n-2)*(m-2)*pp[5];
        printf("%.10e\n", ans);
    }

    return 0;
}