N = int(input())
M = int(input())
X2 = 0
M2 = M
while M2 % 2 == 0:
    M2 //= 2
while M2 % 5 == 0:
    M2 //= 5
if M2 != 1:
    print(-1)
    exit()
S = str(N*10**18/M)
for s in reversed(S):
    if s != "0" and s != ".":
        print(s)
        exit()