import sys

sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()

dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# md = 10**9+7
md = 998244353

n=14
a=80-II()
p0,p1,p2=LI()
p0/=100
p1/=100
p2/=100

dp=[[0]*(n+1) for _ in range(a+1)]
for j in range(n+1):dp[0][j]=j

for y in range(1,a+1):
    for t in range(1,n+1):
        for l in range(t):
            pl=p2
            if l==0:pl=1
            if l==1:pl=p1
            for r in range(l+1,t+1):
                pr = p2
                if r == t: pr = 1
                if r == t-1: pr = p1
                p=pl*pr
                for i in range(l,r):
                    if i==0==t-1:
                        p*=(1-p0)
                    elif i==0 or i==t-1:
                        p*=(1-p1)
                    else:
                        p*=(1-p2)
                dp[y][t]+=dp[y-1][r-l]*p

ans=dp[a][14]*2
print(f"{ans:.10f}")