#include "bits/stdc++.h"

using namespace std;

void solve()
{
	int n;
	cin >> n;
	double p, q;
	cin >> p >> q;
	vector<vector<double>> dp(2, vector<double>(n+2, 0));
	dp[0][1] = 1;
	double ans = 0;
	int reptimes = 100000;
	while(reptimes--)
	{
		vector<vector<double>> nx(2, vector<double>(n+2, 0));
		for (int i = 1; i <= n; i++)
			for (int j = 0; j < 2; j++)
			{
				nx[j^1][i-1] += dp[j][i] * p;
				nx[j^1][i+1] += dp[j][i] * q;
			}
		ans += nx[1][0];
		swap(dp, nx);
	}
	cout << fixed << setprecision(9) << ans << endl;
}

int main()
{
	solve();
	//cout << "yui(*-v・)yui" << endl;
	return 0;
}