codeforces 515C （数学）

#include<bits/stdc++.h>
#define x first
#define y second
#define PB push_back
#define mst(x,a) memset(x,a,sizeof(x))
#define all(a) begin(a),end(a)
#define rep(x,l,u) for(ll x=l;x<u;x++)
#define rrep(x,l,u) for(ll x=l;x>=u;x--)
#define IOS ios::sync_with_stdio(false);cin.tie(0);
using namespace std;
typedef unsigned long long ull;
typedef pair<int,int> PII;
typedef pair<long,long> PLL;
typedef pair<char,char> PCC;
typedef long long ll;
const int N=5010;
const int M=1e6+10;
const int INF=0x3f3f3f3f;
const int MOD=1e9+7;
int cnt[10];
void solve(){
    int n;cin>>n;
    string s;cin>>s;
    rep(i,0,n){
        int u=s[i]-'0';
        if(u==4){
            cnt[2]+=2;
            cnt[3]++;
        }else if(u==6){
            cnt[5]++;
            cnt[3]++;
        }else if(u==8){
            cnt[7]++;
            cnt[2]+=3;
        }else if(u==9){
            cnt[7]++;
            cnt[3]+=2;
            cnt[2]++;
        }
        }else{
            cnt[u]++;
        }
    }
    while(cnt[7]--) cout<<7;
    while(cnt[5]--) cout<<5;
    while(cnt[3]--) cout<<3;
    while(cnt[2]--) cout<<2;
    cout<<endl;
}
int main(){
    IOS;
    //int t;cin>>t;
    //while(t--){
        solve();
    //}
    return 0;
}