N,M = map(int,raw_input().split())
fib = [0]*N
fib[0]=fib[1]=1
for i in xrange(2,N):fib[i] = fib[i-1] + fib[i-2]
dp = {0:0}
for i in xrange(3,N):
	x = fib[N-i]
	tmp_dp = {}
	for k,v in dp.iteritems():
		tmp_dp[k] = v
		nk = k+x
		if nk not in tmp_dp or tmp_dp[nk] > v+1:
			tmp_dp[nk] = v+1
	dp = tmp_dp
k = fib[N-1] - M
print dp[k] if k in dp else -1