n, m = map(int, input().split())

# Calculate the standard Fibonacci sequence up to n
fib = [0] * (n + 1)
fib[1] = 1
if n >= 2:
    fib[2] = 1
for i in range(3, n + 1):
    fib[i] = fib[i-1] + fib[i-2]

fn = fib[n]
d = fn - m

if d < 0:
    print(-1)
elif d == 0:
    print(0)
else:
    # Collect the possible Fib(k) values for each i from 3 to n
    candidates = []
    for i in range(3, n + 1):
        k = n - i + 1
        if k >= 1:
            candidates.append(fib[k])
    
    count = 0
    current_d = d
    for num in candidates:
        if current_d >= num:
            current_d -= num
            count += 1
            if current_d == 0:
                break
    
    print(count if current_d == 0 else -1)