# -*- coding: utf-8 -*-

A = input()
P = map(int,raw_input().strip().split())

memo = [[-1.0 for i in range(20)] for j in range(70)]

# pythonでは確率やリストを前処理しないとキツイです
prob = []
prob.append([]) # N=0
prob.append([P[0]/100.0, (100-P[0])/100.0]) # N=1
V = []
V.append([]) # N=0
V.append([[],[1]]) # N=1

for i in range(2,15):
	prob.append([0]*(1<<i))
	V.append([])
	for mask in range(1<<i):
		p = 1
		for j in range(i):
			if j==0 or j==i-1:
				pr = P[1]/100.0
			else:
				pr = P[2]/100.0
			
			if mask & (1<<j):
				p *= 1-pr
			else:
				p *= pr
		
		prob[i][mask] = p
		v = []
		left = 0
		m = mask
		while m>0:
			if m&1:
				left += 1
			else:
				if left>0:
					v.append(left)
				left = 0
			m >>= 1
		
		if left>0:
			v.append(left)
		V[i].append(v)

# N本並ぶ歯が、Y年後に残る本数の期待値
def func(Y, N):
	if Y == 0:
		return N
	
	if memo[Y][N] >= 0:
		return memo[Y][N]
	
	memo[Y][N] = 0
	for mask in range(1<<N):
		for left in V[N][mask]:
			memo[Y][N] += prob[N][mask] * func(Y-1, left)
	
	return memo[Y][N]


# 上の歯と下の歯の期待値は同じなので、２倍して出力
print "%.9f" % (2.0*func(80-A,14))