/*
ID: marijus1
PROG: calfflac
LANG: C++
*/
#include <string>
#include <fstream>
#include <iostream>
#include <algorithm>
#include <sstream>

using namespace std;


string rev(string s)
{
    return string(s.rbegin(), s.rend());
}

bool valid(char c)
{
    string CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

    return binary_search(CHARS.begin(), CHARS.end(), c);
}

string convert(string s)
{
    string snew;
    int N = s.length();

    for (int i = 0; i < N; i++){
        if (valid(toupper(s[i])))
            snew += toupper(s[i]);
    }

    return snew;
}

string cleanUp(string s)
{
    while ( !valid(toupper(s[0])) )
        s.erase(0,1);

    while ( !valid(toupper(s[s.length()-1])) )
        s.erase(s.length()-1,1);
    return s;
}

int main()
{
    ifstream fin ("calfflac.in");
    ofstream fout ("calfflac.out");

    string original((std::istreambuf_iterator<char>(fin)), std::istreambuf_iterator<char>());

    int len = original.length();
    int longest = 0;
    string answer;

    for (int i = 0; i < len-1; i++){

        int lower(0), upper(0);

        if (len % 2 == 0){
            lower = i;
            upper = i+1;
        } else {
            lower = i;
            upper = i;
        }

        while (lower >= 0 && upper <= len){
            string s2 = original.substr(lower,upper-lower+1);
            string s = convert(s2);

            if (s[0] == s[s.length()-1]){
                lower -= 1;
                upper += 1;
            } else {
                if (s.length() > longest){
                    longest = s.length();
                    answer = s2;
                }
                break;
            }


        }
    }

    fout << longest << endl;
    fout << cleanUp(answer) << endl;

    return 0;
}