#include <bits/stdc++.h>

using namespace std;

int main()
{
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	
	freopen("password.in", "r", stdin);
	freopen("password.out", "w", stdout);
	
	int n, i, x;
	string s;
	int cnt[10];
	
	cin>>n>>s;
	for (i = 0; i < 10; ++i)
		cnt[i] = count(s.begin(), s.end(), ('0' + i));
	x = *max_element(cnt, cnt  + 10);
	vector<string> sols;
	for (i = 0; i < 10; ++i) if (cnt[i] == x)
		sols.push_back(string(cnt[i], '0' + i));
	
	cout<<sols.size()<<'\n';
	for (const auto& x: sols)
		cout<<x<<'\n';
}