#include <iostream>
#include <algorithm>
using namespace std;

int main() {
    freopen("password.in","r",stdin);
    freopen("password.out","w",stdout);

    int n, cnt = 1, best = 1, ans = 0;
    string s;
    cin >> n;
    cin >> s;
    for (int i = 1; i < s.size(); i++) {
        if (s[i] == s[i - 1]) cnt++;
        else {
            best = max(best, cnt);
            cnt = 1;
        }
    }
    best = max(best, cnt);
    cnt = 1;
    for (int i = 1; i < s.size(); i++) {
        if (s[i] == s[i - 1]) cnt++;
        else  cnt = 1;
        if (cnt == best) ans++;
    }
    if (best == 1) ans++;
    cout << ans << endl;
    cnt = 1;
    if (best == 1) cout << s[0] << endl;
    for (int i = 1; i < s.size(); i++) {
        if (s[i] == s[i - 1]) cnt++;
        else  cnt = 1;
        if (cnt == best) {
            for (int j = 0; j < cnt; j++) cout << s[i];
            cout << endl;
        }
    }
    return 0;
}