#include <stdio.h>

long long int n, m, f[80];

int main(void) {
	scanf("%lld%lld", &n, &m);
	
	long long int i;
	f[1] = 1, f[2] = 1;
	for(i = 3; i <= n; i++) {
		f[i] = f[i - 1] + f[i - 2];
	}
	
	long long int r = f[n] - m, counter = 0;
	for(i = n - 2; 1 <= i; i--) {
		if(f[i] <= r) { r -= f[i]; counter++; }
	}
	
	printf("%lld\n", (r == 0 ? counter : -1) );
	
	return 0;
}