#include <iostream>
#include <fstream>
#include<iomanip>
using namespace std;
//////////////////////////////
int main ()
{
    ifstream in("input.txt");
    ofstream out("result.txt");
    char x;
    int q=0;
    if (!in)
    {
        cout<<"Can't open file"<<endl;
        exit(-1);
    }
        while ( in>>x && q!=5)
        {
            out<<x;
                switch (q)
                {
                    case 0: if (x=='A') q=1; else q=5; break;
                    case 1: if (x=='A' || x=='B') q=2; else q=5; break;
                    case 2: if (x=='A') q=3; else q=5; break;
                    case 3: if (x=='A' || x=='B') q=2;
                    else if (x=='C') q=4;
                    else q=5; break;
                    default: q=5; break;
                }
            out<<setw(2)<<q<<endl;
        }
    out<<endl;
    if (q==4) out<<" sequence is element of L"<<endl;
    else out<<"sequence is not element of L"<<endl;
    in.close();
    out.close();
    return 0;
}