#define _CRT_SECURE_NO_WARNINGS
#include "bits/stdc++.h"
//#include "libs.h"
#include <random>
#include <unordered_map>
#include <unordered_set>
//#include <opencv2/core.hpp>
//#include <opencv2/highgui.hpp>
//#include <opencv2/imgproc.hpp>

using namespace std;

//呪文
#define DUMPOUT cerr
#define dump(...) DUMPOUT<<"  ";DUMPOUT<<#__VA_ARGS__<<" :["<<__LINE__<<":"<<__FUNCTION__<<"]"<<endl;DUMPOUT<<"    ";dump_func(__VA_ARGS__)

typedef unsigned uint; typedef long long ll; typedef unsigned long long ull; typedef pair<int, int> pii; typedef pair<ll, ll> pll; typedef pair<double, double> pdd; typedef pair<string, string> pss;
template <typename _KTy, typename _Ty> ostream& operator << (ostream& o, const pair<_KTy, _Ty>& m) { o << "{" << m.first << ", " << m.second << "}"; return o; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& o, const map<_KTy, _Ty>& m) { if (m.empty()) { o << "{ }"; return o; } o << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { o << ", " << *itr; } o << "}"; return o; }
template <typename _KTy, typename _Ty> ostream& operator << (ostream& o, const unordered_map<_KTy, _Ty>& m) { if (m.empty()) { o << "{ }"; return o; } o << "{" << *m.begin(); for (auto itr = ++m.begin(); itr != m.end(); itr++) { o << ", " << *itr; } o << "}"; return o; }
template <typename _Ty> ostream& operator << (ostream& o, const vector<_Ty>& v) { if (v.empty()) { o << "{ }"; return o; } o << "{" << v.front(); for (auto itr = ++v.begin(); itr != v.end(); itr++) { o << ", " << *itr; } o << "}"; return o; }
template <typename _Ty> ostream& operator << (ostream& o, const set<_Ty>& s) { if (s.empty()) { o << "{ }"; return o; } o << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { o << ", " << *itr; } o << "}"; return o; }
template <typename _Ty> ostream& operator << (ostream& o, const unordered_set<_Ty>& s) { if (s.empty()) { o << "{ }"; return o; } o << "{" << *(s.begin()); for (auto itr = ++s.begin(); itr != s.end(); itr++) { o << ", " << *itr; }	o << "}"; return o; }
template <typename _Ty> ostream& operator << (ostream& o, const stack<_Ty>& s) { if (s.empty()) { o << "{ }"; return o; } stack<_Ty> t(s); o << "{" << t.top(); t.pop(); while (!t.empty()) { o << ", " << t.top(); t.pop(); } o << "}";	return o; }
template <typename _Ty> ostream& operator << (ostream& o, const list<_Ty>& l) { if (l.empty()) { o << "{ }"; return o; } o << "{" << l.front(); for (auto itr = ++l.begin(); itr != l.end(); ++itr) { o << ", " << *itr; } o << "}"; return o; }
template <typename _KTy, typename _Ty> istream& operator >> (istream& is, pair<_KTy, _Ty>& m) { is >> m.first >> m.second; return is; }
template <typename _Ty> istream& operator >> (istream& is, vector<_Ty>& v) { for (size_t i = 0; i < v.size(); i++) is >> v[i]; return is; }
namespace aux { // print tuple
	template<typename Ty, unsigned N, unsigned L> struct tp { static void print(ostream& os, const Ty& v) { os << get<N>(v) << ", "; tp<Ty, N + 1, L>::print(os, v); } };
	template<typename Ty, unsigned N> struct tp<Ty, N, N> { static void print(ostream& os, const Ty& v) { os << get<N>(v); } };
}
template<typename... Tys> ostream& operator<<(ostream& os, const tuple<Tys...>& t) { os << "{"; aux::tp<tuple<Tys...>, 0, sizeof...(Tys) - 1>::print(os, t); os << "}"; return os; }

template<typename A, size_t N, typename T> inline void Fill(A(&array)[N], const T &val) { std::fill((T*)array, (T*)(array + N), val); }

void dump_func() { DUMPOUT << endl; }
template <class Head, class... Tail> void dump_func(Head&& head, Tail&&... tail) { DUMPOUT << head; if (sizeof...(Tail) == 0) { DUMPOUT << " "; } else { DUMPOUT << ", "; } dump_func(std::move(tail)...); }

#define PI 3.14159265358979323846
#define EPS 1e-10
#define FOR(i,a,n) for(int i=(a);i<(n);++i)
#define REP(i,n)  FOR(i,0,n)
#define all(j) (j).begin(), (j).end()
#define SZ(j) ((int)(j).size())
#define fake false



#define int long long

int dp[3010][3010];
int pre[3010][3010]; // 左から: 3, 上から: 2, 左上から: 1

string lcs(string a, string b) {
	int m = a.size(), n = b.size();
	a = " " + a;
	b = " " + b;
	int len = 0;
	for (int i = 1; i <= m; i++) for (int j = 1; j <= n; j++) {
		if (a[i] == b[j]) {
			dp[i][j] = dp[i - 1][j - 1] + 1;
			pre[i][j] = 1;
		}
		else if (dp[i - 1][j] < dp[i][j - 1]) {
			dp[i][j] = dp[i][j - 1];
			pre[i][j] = 3;
		}
		else {
			dp[i][j] = dp[i - 1][j];
			pre[i][j] = 2;
		}
	}
	int i = m, j = n;
	string ans;
	while (i && j) {
		if (pre[i][j] == 1) {
			ans.push_back(a[i]);
			i--; j--;
		}
		else if (pre[i][j] == 2)
			i--;
		else
			j--;
	}
	reverse(all(ans));
	return ans;
}

//  @ a b r a c a d a b r a
//@ 0 0 0 0 0 0 0 0 0 0 0 0
//a 0*1 1 1 1 1 1 1 1 1 1 1
//v 0 1 1 1 1 1 1 1 1 1 1 1
//a 0 1 1 1*2 2 2 2 2 2 2 2
//d 0 1 1 1 2 2 2 3 3 3 3 3
//a 0 1 1 1 2 2*3 3 4 4 4 4
//k 0 1 1 1 2 2 3 3 4 4 4 4
//e 0 1 1 1 2 2 3 3 4 4 4 4
//d 0 1 1 1 2 2 3*4 4 4 4 4
//a 0 1 1 1 2 2 3 4*5 5 5 5
//v 0 1 1 1 2 2 3 4 5 5 5 5
//r 0 1 1 2 2 2 3 4 5 5*6 6
//a 0 1 1 2 3 3 3 4 5 5 6*7

signed main() {

	cin.tie(0);
	ios::sync_with_stdio(false);
	
	string s, t;
	cin >> s >> t;

	cout << lcs(s, t) << endl;

	return 0;
}


Measured memory_bytes: 141696