N,M = list(map(int, input().split()))

def fibo(n):
    numbers = [0 for _ in range(N)]
    numbers[0] = 1
    numbers[1] = 1
    for i in range(2,n):
        numbers[i] = numbers[i-1] + numbers[i-2]
    return numbers

numbers = fibo(N)
diff = numbers[N-1] - M

if diff == 0:
    print(0)
    exit(0)
    
if diff < 0:
    print(-1)
    exit(0)

count = 0
for i in reversed(range(0,N-2)):
    if 0 <= diff - numbers[i]:
        diff = diff - numbers[i]
        count = count + 1
        if diff == 0:
            break
            
print(count)