import sys
def MI(): return map(int,sys.stdin.readline().rstrip().split())


N,M = MI()
fib = [0,1,1]
for _ in range(80):
    fib.append(fib[-1]+fib[-2])

X = fib[N]-M
ans = 0
for i in range(N-2,0,-1):
    if X >= fib[i]:
        ans += 1
        X -= fib[i]
print(ans if X == 0 else -1)