x, y = map(int, input().split())
c = 0
while x != y:
    if c < 100:
        if x != 0:
            x, y = x + y,x - y
        else:
            x, y = y, x
        c += 1
    else:
        break
if x == y:
    print(c)
else:
    print(-1)