// yukicoder: 320 眠れない夜に
// 2019.5.19 bal4u

#include <stdio.h>

long long a[82];
int main()
{
	int i, N, ans;
	long long M;
	
	scanf("%d%lld", &N, &M);
	a[1] = 1, a[2] = 1; 
	for (i = 3; i <= N; i++) a[i] = a[i-1]+a[i-2];
	
	ans = 0;
	if (M > a[N]) ans = -1;
	else if (M < a[N]) {
		M = a[N]-M;
		for (i = N-2; i > 0; i--) {
			if (M >= a[i]) M -= a[i], ans++;
		}
	}
	printf("%d\n", ans);
	return 0;
}