#include<cstdio>#include<iostream>#include<algorithm>#include<cstring>#include<cmath>#include<vector>#include<queue>#include<map>#include<set>#include<stack>#include<cstdlib>#include<string>#include<bitset>#define INF 100000000#define fi first#define se second#define debug(x) cout<<#x<<"="<<x<<endlusing namespace std;typedef long long LL;typedef pair<int,int> pii;int c[10][10],a[10];char s[35];int main(){    freopen("david.in","r",stdin);    freopen("david.out","w",stdout);    c[2][2]=1;    c[3][3]=1;    c[4][2]=2,c[4][3]=1;    c[5][5]=1;    c[6][3]=1,c[6][5]=1;    c[7][7]=1;    c[8][2]=3,c[8][7]=1;    c[9][2]=1,c[9][3]=2,c[9][7]=1;    int n,i,j;    cin>>n;    scanf("%s",s+1);    for(i=1;i<=n;i++)    {        for(j=1;j<=9;j++)            a[j]+=c[s[i]-48][j];    }    for(j=9;j;j--)        while(a[j])            printf("%d",j),a[j]--;    cout<<endl;    return 0;}// davidlee1999WTK 2015/// srO myk Orz//ios::sync_with_stdio(false);