#include <iostream>
#include <algorithm>
#include <vector>
#include <string.h>
#include <tuple>
using namespace std;
#define mod (long)(998244353)
#define all(x) (x).begin(), (x).end()
#define bitcount(n) __builtin_popcountl(long(n))
#define fcout cout << fixed << setprecision(15)
#define highest(x) (63 - __builtin_clzl(x))
#define long long long
template<class T> inline void YES(T condition){ if(condition) cout << "YES" << endl; else cout << "NO" << endl; }
template<class T> inline void Yes(T condition){ if(condition) cout << "Yes" << endl; else cout << "No" << endl; }
template<class T> inline void POSS(T condition){ if(condition) cout << "POSSIBLE" << endl; else cout << "IMPOSSIBLE" << endl; }
template<class T> inline void Poss(T condition){ if(condition) cout << "Possible" << endl; else cout << "Impossible" << endl; }
template<class T> inline void First(T condition){ if(condition) cout << "First" << endl; else cout << "Second" << endl; }
template<class T = string, class U = char>int character_count(T text, U character){ int ans = 0; for(U i: text){ ans += (i == character); } return ans; }
long power(long base, long exponent, long module){ if(exponent % 2){ return power(base, exponent - 1, module) * base % module; }else if(exponent){ long root_ans = power(base, exponent / 2, module); return root_ans * root_ans % module; }else{ return 1; }}
struct position{ int y, x; }; position move_pattern[4] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}}; // double euclidean(position first, position second){ return sqrt((second.x - first.x) * (second.x - first.x) + (second.y - first.y) * (second.y - first.y)); }
template<class T, class U> string to_string(pair<T, U> x){ return to_string(x.first) + "," + to_string(x.second); }
template<class itr> void array_output(itr start, itr goal){ string ans; for(auto i = start; i != goal; i++){ ans += to_string(*i) + " "; } ans.pop_back(); cout << ans << endl; }
template<class itr> void cins(itr start, itr goal){ for(auto i = start; i != goal; i++){ cin >> (*i); } }
template<class T> T gcd(T a, T b){ if(a && b){ return gcd(min(a, b), max(a, b) % min(a, b)); }else{ return a; }} template<class T> T lcm(T a, T b){ return a / gcd(a, b) * b; }
struct combination{ vector<long> fact, inv; combination(int sz) : fact(sz + 1), inv(sz + 1){ fact[0] = 1; for(int i = 1; i <= sz; i++){ fact[i] = fact[i - 1] * i % mod; } inv[sz] = power(fact[sz], mod - 2, mod); for(int i = sz - 1; i >= 0; i--){ inv[i] = inv[i + 1] * (i + 1) % mod; } } long C(int p, int q) const{ if(q < 0 || p < q) return 0; return (fact[p] * inv[q] % mod * inv[p - q] % mod); } };

string s, t;

int dp[3010][3010];
tuple<int, int, bool> backpoint[3010][3010];

int LCS(int s_now, int t_now){
    if(s_now == s.size() || t_now == t.size()){
        backpoint[s_now][t_now] = tuple<int, int, bool>(-1, -1, false);
        return 0;
    }else if(dp[s_now][t_now] != -1){
        return dp[s_now][t_now];
    }else if(s[s_now] == t[t_now]){
        backpoint[s_now][t_now] = tuple<int, int, bool>(s_now + 1, t_now + 1, true);
        return dp[s_now][t_now] = LCS(s_now + 1, t_now + 1) + 1;
    }else{
        if(LCS(s_now + 1, t_now) > LCS(s_now, t_now + 1)){
            backpoint[s_now][t_now] = tuple<int, int, bool>(s_now + 1, t_now, false);
        }else{
            backpoint[s_now][t_now] = tuple<int, int, bool>(s_now, t_now + 1, false);
        }
        return dp[s_now][t_now] = max(LCS(s_now + 1, t_now), LCS(s_now, t_now + 1));
    }
}

int main(){
    cin >> s >> t;
    memset(dp, -1, sizeof(dp));
    LCS(0, 0);
    int s_now = 0, t_now = 0;
    while(get<0>(backpoint[s_now][t_now]) != -1){
        if(get<2>(backpoint[s_now][t_now])){
            cout << s[s_now];
        }
        int next_s_now = get<0>(backpoint[s_now][t_now]);
        int next_t_now = get<1>(backpoint[s_now][t_now]);
        s_now = next_s_now;
        t_now = next_t_now;
    }
    cout << endl;
}


Measured memory_bytes: 142336