A, B = map(int, input().split())
A, B = abs(A), abs(B)
ans = 0
Closed = [[False]*20 for i in range(20)]
for a1 in range(20):
    for b1 in range(20):
        x = a1*A + b1*B + 1
        if not 1 <= x < 20:
            continue
        for a2 in range(20):
            for b2 in range(20):
                y = a2*A + b2*B + 1
                if not 1 <= y < 20:
                    continue
                if not Closed[y][x]:
                    Closed[y][x] = True
                    ans += 1/((x+y)**(x+y))
print(ans)