// 1
// 2
// 3
// 4

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>

using namespace std;

// �.�.�.

#define forn(i, n) for (int i = 0; i < (int)(n); i++)

const int N = (int)1e3;

char s[N + 1], t[N + 1];
int sn, tn;

struct State
{
  unsigned short f; // 0 <= f <= N : 10 bit
  unsigned char p;  // 0 <= p <= 2 : 2 bit
} a[N + 2][N + 2]; 

inline void relax( int i, int j, int b, int type )
{
  if (a[i][j].f < b)
    a[i][j].f = b, a[i][j].p = type;
}

void solve()
{
  reverse(s, s + sn);
  reverse(t, t + tn);

  memset(a, 0, sizeof(a));
  forn(i, sn + 1) // i = 0..sn
    forn(j, tn + 1) // j = 0..tn
    {
      if (s[i] == t[j])
        relax(i + 1, j + 1, a[i][j].f + 1, 0);
      relax(i + 1, j, a[i][j].f, 1);
      relax(i, j + 1, a[i][j].f, 2);
    }

  printf("sizeof = %d\n", sizeof(State));
  printf("%d\n", a[sn][tn].f);

  int i = sn, j = tn;
  while (a[i][j].f > 0)
  {
    int type = a[i][j].p;
    //fprintf(stderr, "i = %d, j = %d, type = %d : f = %d\n", i, j, type, a[i][j].f);
    if (type == 0)
      i--, j--, putchar(s[i]);
    else if (type == 1)
      i--;
    else 
      j--;
  }
}

int main()
{
  gets(s);
  gets(t);
  sn = strlen(s);
  tn = strlen(t);
  solve();
  return 0;
}