from functools import lru_cache

memo_y = [p / 200 for p in range(100 + 1)]
memo_n = [(100 - p) / 300 for p in range(100 + 1)]
memo_win = [memo_y[p] + memo_n[p] for p in range(100 + 1)]

@lru_cache(maxsize=None)
def solve(p, q, depth):
    if depth > 20:
        return 0
    
    next_depth = depth + 1
    if depth == 0:
        p0 = 0
        win = memo_win[p0]
        tie_y = memo_y[p0]
        tie_n = memo_n[p0] * solve(p, q, next_depth)
    else:
        p_y = max(0, p - q)
        p_n = min(100, p + q)
        
        win = memo_win[p]
        tie_y = memo_y[p] * solve(p_y, q, next_depth)
        tie_n = memo_n[p] * solve(p_n, q, next_depth)
    
    return win + tie_y + tie_n
    
p, q = map(int, input().split())

print(solve(p, q, 0))