#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
const int N=1e5+5, M=405;
ld f[N], g[N], ct[N], h[N];
ld d[N][M];
int main(){
//	freopen(".in", "r", stdin);
//	freopen(".out", "w", stdout);
	int n, k;
	cin >> n >> k;
	//#
	k=min(k, M-1);
	ld p;
	cin >> p;
	f[0]=g[0]=0;
	for(int i=1; i<=n; ++i){
		f[i]=(p*g[i-1]+1)/(1-p);
		g[i]=g[i-1]+f[i];
//		cerr << f[i] << '\n';
	}
	for(int i=n; i>=1; --i){
		for(int j=0; j<=k; ++j){
			d[i][j]=(p*g[i-1]+(1-p)*d[i+1][j]+1)/(1-p);
			if(j) d[i][j]=min(d[i][j], p*d[i][j-1]+(1-p)*d[i+1][j]+1);
		}
	}
	ld ans=d[1][k];
	printf("%.15LF\n", ans);
	return 0;
}
/*
100000 10
0.0002
*/
/*
fi=p (gi-1+fi) + 1

(1-p)fi=p fi-1+1
fi=(p gi-1 + 1)/(1-p)

100000 1000
0.0002
*/