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]
dif = fib[-1] - M
cnt = 0
for i in xrange(N-3,-1,-1):
	if dif >= fib[i]:dif -= fib[i]; cnt += 1
print cnt if dif == 0 else -1