#include <bits/stdc++.h>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rep2(j,n) for(int j = 0; j < (n); ++j)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define srep2(j,s,t) for (int j = s; j < t; ++j)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) (x = max(x,y))
#define mins(x,y) (x = min(x,y))
#define limit(x,l,r) max(l,min(x,r))
#define lims(x,l,r) (x = max(l,min(x,r)))
#define isin(x,l,r) ((l) <= (x) && (x) < (r))
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcountll
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define bn(x) ((1<<x)-1)
#define dup(x,y) (((x)+(y)-1)/(y))
#define newline puts("")
#define v(T) vector<T>
#define vv(T) v(v(T))
using namespace std;
typedef long long int ll;
typedef unsigned uint;
typedef unsigned long long ull;
typedef pair<int,int> P;
typedef set<int> S;
typedef queue<int> Q;
typedef queue<P> QP;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
inline int in() { int x; scanf("%d",&x); return x;}
template<typename T>inline istream& operator>>(istream&i,v(T)&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(const v(T)&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>inline ostream& operator<<(ostream&o,const v(T)&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>inline istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>inline ostream& operator<<(ostream&o,const pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
template<typename T>inline ll suma(const v(T)& a) { ll res(0); for (auto&& x : a) res += x; return res;}
const double eps = 1e-10;
const ll LINF = 1001002003004005006ll;
const int INF = 1001001001;
#define dame { puts("-1"); return 0;}
#define yn {puts("YES");}else{puts("NO");}
const int MX = 200005;




int main() {
  string a, b;
  int al,bl;
  cin >> a >> b;
  al = sz(a);
  bl = sz(b);
  int dp[al][bl];
  bool aflag = false;
  rep(i,al){
    if(!aflag && b[0] == a[i]){
      dp[i][0] = 1;
      aflag = true;
    } else if (aflag) {
      dp[i][0] = 1;
    } else {
      dp[i][0] = 0;
    }
  }
  bool bflag = false;
  rep(i,bl){
    if(!bflag && a[0] == b[i]){
      dp[0][i] = 1;
      bflag = true;
    } else if (bflag) {
      dp[0][i] = 1;
    } else {
      dp[0][i] = 0;
    }
  }
  
  srep(i,1,min(al,bl)) {
    if(a[i] == b[i]){
      dp[i][i] = dp[i-1][i-1] + 1;
    }else{
      dp[i][i] = max(dp[i-1][i],dp[i][i-1]);
    }

    srep2(j,i+1,al) {
      if(a[j] == b[i]){
        dp[j][i] = dp[j-1][i-1] + 1;
      } else {
        dp[j][i] = max(dp[j-1][i],dp[j][i-1]);
      }
    }

    srep2(j,i+1,bl) {
      if(a[i] == b[j]){
        dp[i][j] = dp[i-1][j-1] + 1;
      } else {
        dp[i][j] = max(dp[i-1][j],dp[i][j-1]);
      }
    }
  }
  

  int x = al -1;
  int y = bl -1;
  string ans = "";

  while(true){
    if(x == 0 && y == 0){
      if(a[x] == b[y] ){
        ans += a[x];
      }
      reverse(rng(ans));
      cout << ans << endl;
      return 0;
    } else if (x == 0 || y == 0) {
      if(a[x] == b[y]) {
        ans += a[x];
        reverse(rng(ans));
        cout << ans << endl;
        return 0;
      }
      x = max(0,x-1);
      y = max(0,y-1);
    } else if (a[x] == b[y]){
      ans += a[x];
      
      if (dp[x][y] == 1) {
        reverse(rng(ans));
        cout << ans << endl;
        return 0;
      }
      x--;
      y--;
    } else if (dp[x][y] == dp[x-1][y]) {
      x--;
    } else if (dp[x][y] == dp[x][y-1]) {
      y--;
    }
  }
  return 0;
}

Measured memory_bytes: 35456