///17571@nith.ac.in @Ankit Verma
#include <bits/stdc++.h>
using namespace std;
#define ff          first
#define ss          second
#define pb          push_back
#define MP          make_pair
#define int         long long
#define ll          long long
#define inf         0x3f3f3f3f
#define MOD         1000000007
#define ld          long double
#define eb          emplace_back
#define pii         pair<int,int>
#define ull         unsigned long long
#define all(v)      v.begin(), v.end()
#define f(i,x,n)    for(int i=x;i<n;i++)
#define fr(i,x,n)   for(int i=x;i>=n;i--)
#define fastio      ios::sync_with_stdio(false)

#define n_l '\n'
template <typename T, size_t N> int SIZE(const T (&t)[N]) { return N; } template<typename T> int SIZE(const T &t) { return t.size(); } string to_string(const string s, int x1 = 0, int x2 = 1e9) { return '"' + ((x1 < s.size()) ? s.substr(x1, x2 - x1 + 1) : "") + '"'; } string to_string(const char* s) { return to_string((string) s); } string to_string(const bool b) { return (b ? "true" : "false"); } string to_string(const char c) { return string({c}); } template<size_t N> string to_string(const bitset<N> &b, int x1 = 0, int x2 = 1e9) { string t = ""; for (int __iii__ = min(x1, SIZE(b)),  __jjj__ = min(x2, SIZE(b) - 1); __iii__ <= __jjj__; ++__iii__) { t += b[__iii__] + '0'; } return '"' + t + '"'; } template <typename A, typename... C> string to_string(const A (&v), int x1 = 0, int x2 = 1e9, C... coords); int l_v_l_v_l = 0, t_a_b_s = 0; template <typename A, typename B> string to_string(const pair<A, B> &p) { l_v_l_v_l++; string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; l_v_l_v_l--; return res; } template <typename A, typename... C> string to_string(const A (&v), int x1, int x2, C... coords) { int rnk = rank<A>::value; string tab(t_a_b_s, ' '); string res = ""; bool first = true; if (l_v_l_v_l == 0) res += n_l; res += tab + "["; x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v)); auto l = begin(v); advance(l, x1); auto r = l; advance(r, (x2 - x1) + (x2 < SIZE(v))); for (auto e = l; e != r; e = next(e)) { if (!first) { res += ", "; } first = false; l_v_l_v_l++; if (e != l) { if (rnk > 1) { res += n_l; t_a_b_s = l_v_l_v_l; }; } else { t_a_b_s = 0; } res += to_string(*e, coords...); l_v_l_v_l--; } res += "]"; if (l_v_l_v_l == 0) res += n_l; return res; } void dbgm() {;} template<typename Heads, typename... Tails> void dbgm(Heads H, Tails... T) { cout << to_string(H) << " | "; dbgm(T...); }
#define debug(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgm(__VA_ARGS__); cout << endl

void IO() {
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}

const int MAXN = 3100;
int dp[MAXN][MAXN];
pii nxt[MAXN][MAXN];
char chosen[MAXN][MAXN];
string s, t;
int solve(int i, int j) {
	int &ans = dp[i][j];
	if (i == 0 or j == 0) {
		return 0;
	}
	if (ans != -1)
		return ans;
	if (s[i - 1] == t[j - 1]) {
		nxt[i][j] = {i - 1, j - 1};
		chosen[i][j] = s[i - 1];
		return ans = 1 + solve(i - 1, j - 1);
	}
	ans = max(solve(i - 1, j), solve(i, j - 1));
	if (ans != -1) {
		if (dp[i - 1][j] > dp[i][j - 1]) {
			nxt[i][j] = {i - 1, j};
		} else {
			nxt[i][j] = {i, j - 1};
		}
	}
	return ans;
}

int32_t main() {
	//IO();
	fastio;
	cin.tie(nullptr);
	cout.tie(nullptr);
	cin >> s >> t;
	memset(dp, -1, sizeof dp);
	memset(chosen, '#', sizeof chosen);
	int mlen = solve(s.size(), t.size());
	if (mlen) {
		int x = s.size(); int y = t.size();
		string res;
		while (x > 0 && y > 0) {
			if (x > 0 && y > 0 && chosen[x][y] != '#')
				res += chosen[x][y];
			auto p = nxt[x][y];
			x = p.ff; y = p.ss;
		}
		reverse(all(res));
		cout << res << endl;

	}
	return 0;
}


Measured memory_bytes: 233088