#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return true; } return false; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return true; } return false; }
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define mp make_pair
#define si(x) int(x.size())
const int mod=998244353,MAX=1005,INF=15<<26;

double dp[MAX][MAX];

int main(){
    
    std::ifstream in("text.txt");
    std::cin.rdbuf(in.rdbuf());
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int H,W;
    double P;cin>>H>>W>>P;
    for(int i=H-1;i>=0;i--){
        for(int j=W-1;j>=0;j--){
            if(i==H-1){
                if(j==W-1) continue;
                
                dp[i][j]=dp[i][j+1]+P/4;
            }else if(j==W-1){
                dp[i][j]=dp[i+1][j]+P/4;
            }else{
                {
                    double diff=dp[i+1][j]-dp[i][j+1];
                    if(diff<=0){
                        dp[i][j]+=dp[i+1][j];
                    }else if(diff>=P){
                        dp[i][j]+=dp[i][j+1]+P/2;
                    }else{
                        dp[i][j]+=(dp[i+1][j]*(P-diff)+(dp[i][j+1]+(diff/2))*diff)/P;
                    }
                }
                
                {
                    double diff=dp[i][j+1]-dp[i+1][j];
                    if(diff<=0){
                        dp[i][j]+=dp[i][j+1];
                    }else if(diff>=P){
                        dp[i][j]+=dp[i+1][j]+P/2;
                    }else{
                        dp[i][j]+=(dp[i][j+1]*(P-diff)+(dp[i+1][j]+(diff/2))*diff)/P;
                    }
                }
                
                dp[i][j]/=2;
            }
        }
    }
    
    cout<<fixed<<setprecision(25)<<dp[0][0]<<endl;
}