#include <string>
#include <vector>
#include <algorithm>
#include <numeric>
#include <set>
#include <map>
#include <queue>
#include <iostream>
#include <sstream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstring>
#include <cctype>
#include <cassert>
#include <limits>
#include <functional>
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
#if defined(_MSC_VER) || __cplusplus > 199711L
#define aut(r,v) auto r = (v)
#else
#define aut(r,v) __typeof(v) r = (v)
#endif
#define each(it,o) for(aut(it, (o).begin()); it != (o).end(); ++ it)
#define all(o) (o).begin(), (o).end()
#define pb(x) push_back(x)
#define mp(x,y) make_pair((x),(y))
#define mset(m,v) memset(m,v,sizeof(m))
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3fLL
using namespace std;
typedef vector<int> vi; typedef pair<int,int> pii; typedef vector<pair<int,int> > vpii; typedef long long ll;
template<typename T, typename U> inline void amin(T &x, U y) { if(y < x) x = y; }
template<typename T, typename U> inline void amax(T &x, U y) { if(x < y) x = y; }

int N;
double p0, p1, p2;
const int X = 14;
double memo[21][X+1];

double rec(int i, int j) {
	double &r = memo[i][j];
	if(r == r) return r;
	if(i == N) return r = j;
	r = 0;
	rep(k, 1 << j) {
		double p = 1;
		rep(l, j) {
			bool a = l+1 < j, b = 0 <= l-1;
			bool c = k >> l & 1;
			if(!a && !b)
				p *= c ? 1 - p0 : p0;
			else if(!a || !b)
				p *= c ? 1 - p1 : p1;
			else
				p *= c ? 1 - p2 : p2;
		}
		if(p == 0) continue;

		double sum = 0;
		{	bool c = false; int len = 0;
			rep(l, j+1) {
				bool b = k >> l & 1;
				if(c && !b)
					sum += rec(i+1, len);
				if(b) ++ len; else len = 0;
				c = b;
			}
		}
		r += p * sum;
	}
	return r;
}

int main() {
	int A, P0, P1, P2;
	cin >> A >> P0 >> P1 >> P2;
	N = 80 - A;
	p0 = P0 / 100., p1 = P1 / 100., p2 = P2 / 100.;
	mset(memo, -1);
	double ans = rec(0, X) * 2;
	printf("%.10f\n", ans);
	return 0;
}