var
  s1,s2:string;
  i,j:integer;
  f:array[1..255,1..255] of longint;
  b:array[1..255,1..255] of string;
begin
  readln(s1);readln(s2);
  for i:=1 to length(s1) do f[i,0]:=0;
  for j:=1 to length(s2) do f[0,j]:=0;
  for i:=1 to length(s1) do
  for j:=1 to length(s2) do
  begin
    if s1[i]=s2[j] then
    begin
      f[i,j]:=f[i-1,j-1]+1;
      b[i,j]:=b[i-1,j-1]+s1[i];
    end else
    if f[i-1,j]>f[i,j-1] then
    begin
      f[i,j]:=f[i-1,j];
      b[i,j]:=b[i-1,j];
    end else
    begin
      f[i,j]:=f[i,j-1];
      b[i,j]:=b[i,j-1];
    end;
  end;
  writeln(f[length(s1),length(s2)]);
  writeln(b[length(s1),length(s2)]);
end.