#include <bits/stdc++.h>
#include <set>
#include <cstdio>
#include <vector>
#include <iostream>
#include <utility>

#define fir first
#define sec second
#define get(n) scanf("%d",&n);
#define gets(s) string s;cin >> (s);
#define All(s) (c).begin(), (c).end()
#define chmin(x, y) x = std::min(x, y);
#define chmax(x, y) x = std::max(x, y);
#define rep(i, j) for (int (i)=0;(i)<(j);(i)++)
#define repk(i, j, k) for(int (i)=(j);(i)<(k);(i)++)
#define downfor(i, j, k) for (int (i)=(j);i>(k);i--)
#define dump(x)  cout << #x << " = " << (x) << endl;
#define debug(x) cout << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;
typedef long long int ll;
const ll INF = 10241024;
ll max_n = 2*1e5;
int K,N;
std::vector<int> primenum(max_n);

void input(){
    std::cin >> N >> K;
}
void prime(){
    primenum.push_back(2);
    primenum.push_back(3);
    int rn = sqrt(N);
    int loc = 2;
    for(int i = 5;i<=rn;i++){
        for(int j=1;j<=loc;j++){
            int b = primenum[j];
            if(i % b == 0)
            {
                break;
            }
            if(j == loc)
            {
            loc++;
            primenum.push_back(i);
            }
        }
    }
}

int hash(int a){
    while(a <= 9){
        int b = 0;//temporary value hash
        int aa = a;//
        downfor(i, 5, 0){//5 to 1
            int j = pow(10, i);
            int k = floor(aa/j);
            if(k != 0)
            {
                b += k;
                aa -= j * k;
            }
        }
        a = b;
    }
    return a;
}

void solve(){
    input();
    prime();
    std::vector<int> a;
    int rn = sqrt(N);
    for(int i=0;i<=rn;i++){
        if(primenum[i] >= K)
        {
            int s = hash(primenum[i]);
            a.push_back(s);
        }
    }
    
    int ans = 0;
    int c = 1;
    rep(i, a.size()){
        if(a[i] != a[i+1])
        {
            c++;
        }
        if(a[i] == a[i+1])
        {
            chmax(ans , c);
            c = 1;
        }
    }

    std::cout << ans << std::endl;
        
}
int main () {
    solve();
    return 0;
}