#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <sstream>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <numeric>
#include <cctype>
#include <tuple>
#include <array>
#include <climits>
#include <bitset>
#include <cassert>
#include <unordered_map>

#ifdef _MSC_VER
#include <agents.h>
#endif

#define FOR(i, a, b) for(int i = (a); i < (int)(b); ++i)
#define rep(i, n) FOR(i, 0, n)
#define ALL(v) v.begin(), v.end()
#define REV(v) v.rbegin(), v.rend()
#define MEMSET(v, s) memset(v, s, sizeof(v))
#define UNIQUE(v) (v).erase(unique(ALL(v)), (v).end())
#define MP make_pair
#define MT make_tuple

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int, int> P;

double dp[22][22];

double p[3];

double rec(int n, int rem){
	if (!n) return rem;
	double &res = dp[n][rem];
	if (res >= -.5) return res;

	if (rem == 1) return res = (1 - p[0])*rec(n - 1, rem);

	res = 0;
	rep(i, 1 << rem){
		double pp = 1;
		rep(j, rem){
			if (i >> j & 1) pp *= j == 0 || j == rem - 1 ? 1 - p[1] : 1 - p[2];
			else pp *= j == 0 || j == rem - 1 ? p[1] : p[2];
		}
		double ex = 0;
		int run = 0;
		rep(j, rem){
			if (i >> j & 1) ++run;
			else ex += rec(n - 1, run), run = 0;
		}
		ex += rec(n - 1, run), run = 0;
		res += pp*ex;
	}
	return res;
}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	cout.setf(ios::fixed);
	cout.precision(20);

	int n;
	cin >> n;
	n = 80 - n;
	rep(i, 3) cin >> p[i];
	rep(i, 3) p[i] /= 100;

	rep(i, 22) rep(j, 22) dp[i][j] = -1;

	cout << rec(n, 14) * 2 << endl;
}