import sys

sys.setrecursionlimit(10 ** 6)
from bisect import *
from collections import *
from heapq import *

def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def SI(): return sys.stdin.readline()[:-1]
def LLI(rows_number): return [LI() for _ in range(rows_number)]
int1 = lambda x: int(x) - 1
def MI1(): return map(int1, sys.stdin.readline().split())
def LI1(): return list(map(int1, sys.stdin.readline().split()))
p2D = lambda x: print(*x, sep="\n")
dij = [(0, 1), (1, 0), (0, -1), (-1, 0)]

def main():
    n, m = MI()
    fibo = [1, 1]
    for i in range(n - 2): fibo.append(fibo[-1] + fibo[-2])
    #print(fibo)
    d = fibo[-1] - m
    if d < 0:
        print(-1)
        exit()
    ans = 0
    i = n - 3
    while i >= 0 and d:
        while fibo[i] > d: i -= 1
        if i<0:
            print(-1)
            exit()
        d -= fibo[i]
        i -= 1
        ans += 1
    print(ans)

main()