class nwp {
    String s1;
    String s2;
    int[][] tab;
    int dlugosc=0;
    public nwp(String s1, String s2) {
        this.s1 = s1;
        this.s2 = s2;
         this.tab = new int[s1.length()][s2.length()];
         generate();
    }
    private void generate(){
        for(int i=0;i<s1.length();i++){
            for(int j=0;j<s2.length();j++){
                if(s1.charAt(i) == s2.charAt(j)){
                    if(i>0&&j>0)tab[i][j] = tab[i-1][j-1]+1;
                    else tab[i][j]= 1;
                }else{
                    if(i>0&&j>0)tab[i][j]= Math.max(tab[i-1][j],tab[i][j-1]);
                    else if(i>0&&j<=0)tab[i][j]= Math.max(tab[i-1][j],0);
                    else if(i<=0&&j>0)tab[i][j]= Math.max(0,tab[i][j-1]);
                }
            }
        }
    }
    public void print(){
        System.out.print("\nWyglad Tablicy:\n  ");
        for (int x=0;x<s2.length();x++){
            System.out.print(s2.charAt(x) + " ");
        }
        System.out.println("");
        for(int i=0;i<s1.length();i++){
            System.out.print(s1.charAt(i) + " ");
            for(int j=0;j<s2.length();j++){
                System.out.print(tab[i][j] + " ");
            }
            System.out.println("");
        }
        getNWP();
    }
    private void getNWP(){
        dlugosc = tab[s1.length()-1][s2.length()-1];
        int x=s1.length()-1;
        int y=s2.length()-1;
        String nwp = "";
        int i=0;
        System.out.println(dlugosc);
        boolean done=false;
        int iloscZakretow=0;
        int[][] zakret = new int[Math.max(s1.length(),s2.length())][Math.max(s1.length(),s2.length())];
        while(done==false){
		//gurwaaaa
            if(x !=0 && y != 0) {
                if (tab[x][y] > Math.max(tab[x - 1][y], tab[x][y - 1])) {
                    nwp = nwp + s1.charAt(x);
                    x = x - 1;
                    y = y - 1;
                } else if (tab[x][y] == tab[x - 1][y] && tab[x][y] != tab[x][y - 1]) {
                    x = x - 1;
                } else if (tab[x][y] == tab[x][y - 1] && tab[x][y] != tab[x - 1][y]) {
                    y = y - 1;
                } else {
                    y = y - 1;
                }
            }if(x==0 && y==0)nwp = nwp + s1.charAt(x);
            else if(y==0 && tab[x-1][y]==tab[x][y])x--;
            else if(y ==0 && tab[x-1][y] < tab[x][y]){
                nwp = nwp + s1.charAt(x);
            }
            else if(x==0 && tab[x][y-1]==tab[x][y])y--;
            else if(x==0 && tab[x][y-1] < tab[x][y]){
                nwp = nwp + s1.charAt(x);
            }

            if(nwp.length()==dlugosc){
                System.out.println(reverseString(nwp));
                break;

            }
        }
    }
    private String reverseString(String x){
        int dl = x.length();
        String reversed = "";
        for(int i=dlugosc-1;i>=0;i--){
            reversed = reversed + x.charAt(i);
        }
        return reversed;
    };
}

public class Main {

    public static void main(String[] args) {
        nwp m = new nwp("ffbbd","dbbff");
        m.print();
    }
}