# include <iostream>
#include <stdio.h>
using namespace std;
int a[10];
int main()
{
freopen("password.in","r",stdin);
freopen("password.out","w",stdout);
int n;
cin>>n;
int i,x;
char ch;
for(i=1;i<=n;i++)
{
    cin>>ch;
    x=ch-'0';
    a[x]++;
}
int t=0,br=0;
for(i=0;i<=9;i++)
{
    if(a[i]==t)br++;
    if(a[i]>t){t=a[i];br=1;}
}
cout<<br<<endl;
int j;
for(i=0;i<=9;i++)
{
    if(a[i]==t)
    {
        for(j=1;j<=t;j++)
            cout<<i;
        cout<<endl;
    }
}

return 0;
}