import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def FI(): return float(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MF(): return map(float, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
inf = 10**16
# md = 998244353
md = 10**9+7

n = II()
p = FI()
q = FI()
dp = [0]*(n+1)*2
ans = 0
dp[1] = 1
loop = 10000
for _ in range(loop):
    ndp = [0]*(n+1)*2
    ans += dp[0]*q+dp[1]*p
    ndp[3] += dp[0]*p+dp[1]*q
    for i in range(1, n):
        ndp[i*2-2] += dp[i*2]*q+dp[i*2+1]*p
        ndp[i*2+3] += dp[i*2]*p+dp[i*2+1]*q
    dp = ndp

print(ans)