#include "cstring"
#include "stdlib.h"
#include "map"
#include "string"
#include "iostream"
#include "set"
#include "queue"
#include "vector"
#define FOP freopen("input.txt","r",stdin)
#define Met(x,y) memset(x,y,sizeof x)
#define L index*2
#define R index*2+1
using namespace std;
typedef long long ll;
const ll MAXN=5e5+100;
const ll MOD=1e9+7;
ll fra[20];
void ()
{
	fra[0]=1;
	for(int i=1;i<20;++i)
	    fra[i]=fra[i-1]*i;
	
}
ll calu(ll lim)
{
	bool ret=0;
	ll res=0;
	for(int i=1;i<=12 && !ret;++i)
        for(int j=0;j<(1<<i) && !ret;++j)
        {
            ll digit=1;
            ll tem=j;
            ll cs=0;
            for(int k=0;k<i;++k)
            {
                if(tem%2)
                    cs+=digit*7;
                else cs+=digit*4;
                tem/=2;
                digit*=10;
            }
			if(cs<=lim) res++;
			if(cs>=lim) ret=0;
        }
	return res;
}
ll permute[20];
bool judge(ll num)
{
	while (num) {
		if(num%10!=4 && num%10!=7)
			return 0;
		num/=10;
	}
	return 1;
}
int main(int argc, char const *argv[]) {
	// FOP;
	init();
	ll n,kth;
	cin>>n>>kth;
	ll ans=calu(n- 15);
	// cout<<ans<<endl;
	ll digit=min(15LL,n);
	bool used[20];
	Met(used,0);
	kth--;
	for(int i=0;i<digit;++i)
	{
	    ll tem=kth/fra[digit-i-1];
		// printf("%lld %lldn", kth,fra[digit-i-1]);
		kth%=fra[digit-i-1];
		// printf("%lld %lldn", kth,fra[digit-i-1]);
		if(tem>=digit-i)
		{
			puts("-1");
			return 0;
		}
		for(int j=0;j<20;++j)
		{
		    if(used[j])
				continue;
			if(!tem)
			{
				permute[i]=j;
				used[j]=1;
				break;
			}
			tem--;
		}
		// for(int j=0;j<20;++j)
		//     printf("%d ",used[j]);
		// puts("");
		// printf("%lldn",permute[i]+1);
	}
	ll cnt=0;
	for(int i=max(1LL,n-14),cnt=0;i<=n;++i,cnt++)
	{
		// cout<<max(1LL,n-14)+permute[i-max(1LL,n-14)]<<endl;
		// cout<<i<<endl;
		ans+=judge(max(1LL,n-14)+permute[i-max(1LL,n-14)])&judge(i);
	}
	cout<<ans<<endl;
	return 0;
}