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//
#include <bits/stdc++.h>
#define rep(i,a,b) for(int i=a;i<(b);++i)
#define erep(i,a,b) for(int i=a;i<=(b);++i)
#define per(i,a,b) for(int i=(a);i>(b);--i)
#define eper(i,a,b) for(int i=(a);i>=b;--i)
#define fore(i, x, a) for(auto &&x:a) 
#define ITR(i,b,e) for(auto i=(b);i!=(e);++i)
#define IN(i,a,b) (a)<=(i) && (i)<(b)
#define debug(x)  cout << #x << " = " << (x) << endl;
#define pb push_back
#define mp make_pair
#define MOD 1000000007
#define ALL(x) begin(x),end(x)
#define F first
#define S second
#define debug(x)  cout << #x << " = " << (x) << endl;
const int inf=1001001001; const long long INF=1001001001001001001;
using namespace std;
using ll = long long;
using pii = pair<int,int>;
using vii = vector<int>;
using vll = vector<ll>;
template<class T>using  PS_queue = priority_queue<T, vector<T>, greater<T> >;
template<class T>using vv = vector<T>;
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a = b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a = b; return 1; } return 0; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){fill( (T*)array, (T*)(array+N), val );}
template<class T> ostream& operator<<(ostream &os,const vector<T> &v) {
    ITR(i,begin(v),end(v))os<<*i<<(i==end(v)-1?"":" ");return os;}
template<class T> istream& operator>>(istream &is,vector<T> &v) {
    ITR(i,begin(v),end(v)) is>>*i;return is;}
template<class T,class U> istream& operator>>(istream &is, pair<T,U> &p) {
    is>>p.first>>p.second;return is;}
template<class T>T gcd(T a, T b){ return b ? gcd(b, a % b) : a; }
template<class T>T lcm(T a, T b){ return a / gcd(a, b) * b; }
struct edge { int to, from, cost; };
int dy[]={0, 1, -1, 0}; int dx[]={1, 0, 0, -1};

string s, t;
int dp[3001][3001];
int main() {
 cin.tie(0);
 ios::sync_with_stdio(false);
  cin >> s >> t;
  int n = s.size(), m = t.size();
  set<int> S;
  rep(i, 0, n) { 
    rep(j, 0, m) {
      if (s[i] == t[j]) {
        dp[i+1][j+1] = dp[i][j] + 1;
        S.insert(i);
      }
      else {
        if (dp[i][j+1] < dp[i+1][j]) {
          dp[i+1][j+1] = dp[i+1][j];
        } else {
          dp[i+1][j+1] = dp[i][j+1];
        }
      }
    }
  }
  string ans = "";
  while (n > 0 && m > 0) {
    if (dp[n][m] == dp[n-1][m]) n--;
    else if (dp[n][m] == dp[n][m-1]) m--;
    else {
      ans += s[n-1];
      n--, m--;
    }
  }
  rep(i, 0, ans.size()) {
    cout << ans[ans.size()-1-i];
  }
  cout << "\n";
  return 0;
}



Measured memory_bytes: 35584