def experiment():
    import numpy as np
    fib = [1] * 2
    for _ in range(80):
        fib.append(fib[-1] + fib[-2])

    choose = np.random.randint(0, 5, size=80)
    val = sum(fib[i] for i, c in enumerate(choose) if c == 0)

    print(val)

    # greedy?
    count = 0
    for f in reversed(fib):
        if val >= f:
            val -= f
            count += 1
    print(val, count, np.sum(choose == 0))


def main():
    n, m = list(map(int, input().split()))
    fib = [1] * 2
    for _ in range(n - 2):
        fib.append(fib[-1] + fib[-2])

    val = fib[n - 1] - m
    if val < 0:
        return -1

    count = 0
    for f in reversed(fib[:-2]):
        if val >= f:
            val -= f
            count += 1
    if val != 0:
        return -1
    return count


# experiment()
print(main())