#include<iostream>
#include<math.h>

#define REP(i,N) for(int i=0,__i=N;i<__i;++i)

long long N,M;
double P;



bool input(){
	using namespace std;
	cin>>N>>M;
	cin>>P;
	if(N<1||N>pow(10,9)||M<1||M>pow(10,9)||P<0||P>1)
		return false;
	return true;
}

double solve(){
	double sum_=0;
	int count;
	REP(i,N)
		REP(j,M){
		count=0;
		if(i>0)
			count++;
		if(i<N-1)
			count++;
		if(j>0)
			count++;
		if(j<M-1)
			count++;
		sum_+=P*pow(P,count);
		}
	return sum_;
}

int main(){
	using namespace std;
	if(!input())
		return -1;
	double res=solve();
	printf("%.10lf\n",res);
}