#include <bits/stdc++.h>
#define filein(str) freopen(str, "r", stdin)
#define fileout(str) freopen(str, "w", stdout);
using namespace std;

int main() {
	ios::sync_with_stdio(false);
	cin.tie(NULL);

	filein("password.in");
    fileout("password.out");

    int n;
    cin >> n;
    string s;
    cin >> s;

    if(n == 1) {
        cout << 1 << endl << s << endl;
        return 0;
    }

    int len = 1, maxLen = 0;
    for(int i = 1; i < n; i++) {
        if(s[i] == s[i - 1]) len++;
        else len = 1;

        maxLen = max(maxLen, len);
    }

    vector<char> ans;
    if(maxLen == 1) {
        ans.push_back(s[0]);
    }

    len = 1;
    for(int i = 1; i < n; i++) {
        if(s[i] == s[i - 1]) len++;
        else len = 1;

        if(len == maxLen) {
            ans.push_back(s[i]);
        }
    }

    cout << ans.size() << endl;
    for(int i = 0; i < ans.size(); i++) {
        for(int j = 0; j < maxLen; j++) cout << ans[i];
        cout << endl;
    }

	return 0;
}