#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

// probability s -> t
double prob(vector<int>& P, int s, int t, int len){
	s <<= 1;
	t <<= 1;
	if( (s|t) > s ) return 0.0;
	double ret = 1.0;
	int mask = 0b111;
	for(int i=1; i<=len; i++){
		if( (s&(1<<i)) == 0 ) continue;
		int my_s = ( s>>(i-1) ) & mask;
		if( my_s == 0b010 ){
			if( (t&(1<<i)) == 0){
				ret *= P[0] * 0.01;
			}else{
				ret *= 1 - P[0] * 0.01;
			}
		}else if( my_s == 0b111 ){
			if( (t&(1<<i)) == 0){
				ret *= P[2] * 0.01;
			}else{
				ret *= 1 - P[2] * 0.01;
			}
		}else{
			if( (t&(1<<i)) == 0){
				ret *= P[1] * 0.01;
			}else{
				ret *= 1 - P[1] * 0.01;
			}
		}
	}
	return ret;
}

double dfs(vector<int>& P, vector<vector<double>>& memo, int s, int len, int y){
	if(memo[y][len] >= 0) return memo[y][len];
	if(y==0){
		return len;
	}
	//部分集合列挙
	double ret = 0.0;

	int sub = s;
	do{
		double p = prob(P, s, sub, len);

		double E_ = 0.0;
		int last_len = 0;
		for(int i=0; i<len; i++){
			if((sub >> i) & 1){
				last_len++;
			}else{
				E_ += dfs(P, memo, (1<<last_len)-1, last_len, y-1);
				last_len = 0;
			}
		}
		if(last_len > 0){
			E_ += dfs(P, memo, (1<<last_len)-1, last_len, y-1);
			last_len = 0;
		}

		ret += E_ * p;

		sub = (sub-1) & s;
	}while( sub != s );

	memo[y][len] = ret;

	return ret;
}

int main(){
	int A;
	cin >> A;
	vector<int> P(3);
	cin >> P[0] >> P[1] >> P[2];

	vector<vector<double>> memo(25, vector<double>(15, -1));

	double ans = dfs(P,memo, (1<<14)-1, 14, 80-A) * 2;

	printf("%.10f\n", ans);
	return 0;
}