#include<bits/stdc++.h>
using namespace std;
vector<int>prime;
vector<int>curr;
vector<vector<int>>all;
bool isprime(int n){
    if(n<2)return false;
    for(int i=2;i<=sqrt(n);i++){
        if(n%i==0)return false;
    }
    return true;
}
void backtrack(int index,int sum){
    if(sum==t){
        all.push_back(curr);
        return;
    }
    int n=prime.size();
    if(sum>t || index>n) return;
    curr.push_back(prime[index]);
    backtrack(index+1,sum+prime[index]);
    curr.pop_back();
    
    backtrack(index+1,sum);
}
int main(){
    int s,t;
    cin>>s>>t;
    for(int i=s;i<=t;i++){
        if(isprime(i)) prime.push_back(i);
    }
    backtrack(0,0);
    for(int i=0;i<all.size();i++){
        for(int j=0;j<all[i].size();j++){
            cout<<all[i][j];
        }
    }
}