#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pii;
typedef pair<double,double> pdd;
#define MEM(a, b) memset(a, (b), sizeof(a))
#define SZ(i) ll(i.size())
#define FOR(i, j, k, in) for (ll i=j ; i<k ; i+=in)
#define RFOR(i, j, k, in) for (ll i=j ; i>=k ; i-=in)
#define REP(i, j) FOR(i, 0, j, 1)
#define REP1(i,j) FOR(i, 1, j+1, 1)
#define RREP(i, j) RFOR(i, j, 0, 1)
#define ALL(_a) _a.begin(),_a.end()
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define X first
#define Y second
#ifdef tmd
#define debug(...) do{\
    fprintf(stderr,"%s - %d (%s) = ",__PRETTY_FUNCTION__,__LINE__,#__VA_ARGS__);\
    _do(__VA_ARGS__);\
}while(0)
template<typename T>void _do(T &&_x){cerr<<_x<<endl;}
template<typename T,typename ...S> void _do(T &&_x,S &&..._t){cerr<<_x<<" ,";_do(_t...);}
template<typename _a,typename _b> ostream& operator << (ostream &_s,const pair<_a,_b> &_p){return _s<<"("<<_p.X<<","<<_p.Y<<")";}
template<typename It> ostream& _OUTC(ostream &_s,It _ita,It _itb)
{
    _s<<"{";
    for(It _it=_ita;_it!=_itb;_it++)
    {
        _s<<(_it==_ita?"":",")<<*_it;
    }
    _s<<"}";
    return _s;
}
template<typename _a> ostream &operator << (ostream &_s,vector<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a> ostream &operator << (ostream &_s,set<_a> &_c){return _OUTC(_s,ALL(_c));}
template<typename _a,typename _b> ostream &operator << (ostream &_s,map<_a,_b> &_c){return _OUTC(_s,ALL(_c));}
template<typename _t> void pary(_t _a,_t _b){_OUTC(cerr,_a,_b);cerr<<endl;}
#define IOS()
#else
#define debug(...)
#define pary(...)
#define endl '\n'
#define IOS() ios_base::sync_with_stdio(0);cin.tie(0)
#endif

template<class T> inline bool cmax(T &a, const T &b) { return b > a ? a = b, true : false; }
template<class T> inline bool cmin(T &a, const T &b) { return b < a ? a = b, true : false; }
template<class T> using MaxHeap = priority_queue<T>;
template<class T> using MinHeap = priority_queue<T, vector<T>, greater<T>>;

const ll MOD=1000000007;
const ll INF=0x3f3f3f3f3f3f3f3f;
const ll MAXN=3002;
const ll MAXLG=__lg(MAXN)+2;

string s,t;
ll dp[MAXN][MAXN];
ll src[MAXN][MAXN];
/********** Good Luck :) **********/
int main()
{
    IOS();
    cin >> s >> t;
    REP (i,SZ(s)) {
        REP (j,SZ(t)) {
            if (i == 0 && j == 0) {
                src[i][j] = 0;
            } else {
                if (i == 0) {
                    src[i][j] = -1;
                } else if (j == 0) {
                    src[i][j] = 1;
                } else {
                    src[i][j] = dp[i-1][j] > dp[i][j-1] ? 1 : -1;
                }
            }
            if (s[i] == t[j]) {
                dp[i][j] = ((i>0 && j>0) ? dp[i-1][j-1] : 0) + 1;

            } else {
                dp[i][j] = max((i?dp[i-1][j]:0),(j?dp[i][j-1]:0));
            }
        }
    }

    ll ptrs = SZ(s) - 1;
    ll ptrt = SZ(t) - 1;
    string ans;
    while (ptrs >= 0 && ptrt >= 0) {
        if (s[ptrs] == t[ptrt]) {
            ans.push_back(s[ptrs]);
            ptrs--,ptrt--;
        } else if (src[ptrs][ptrt] == 1) {
            ptrs--;
        } else if (src[ptrs][ptrt] == -1) {
            ptrt--;
        } else {
            break;
        }
    }

    reverse(ALL(ans));
    REP (i,SZ(ans)) {
        cout << ans[i];
    }
    cout << endl;
    return 0;
}


Measured memory_bytes: 141056