import std.stdio, std.string, std.conv;
import std.range, std.algorithm, std.array, std.typecons, std.container;
import std.math, std.numeric, core.bitop;

enum inf = 10L^^15;

void main() {
    auto s = readln.chomp;
    auto t = readln.chomp;

    auto n = s.length.to!int;
    auto m = t.length.to!int;

    auto dp = new int[][](n + 1, m + 1);

    foreach (i ; 1 .. n + 1) {
        foreach (j ; 1 .. m + 1) {
            dp[i][j] = max(dp[i-1][j], dp[i][j-1]);
            if (s[i-1] == t[j-1]) {
                dp[i][j] = max(dp[i][j], dp[i-1][j-1] + 1);
            }
        }
    }

    debug {
        writefln("%(%s\n%)", dp);
    }

    int a = n;
    int b = m;
    string ans;

    while (a > 0 && b > 0) {
        if (s[a-1] == t[b-1]) {
            ans ~= s[a-1];
            a--;
            b--;
            continue;
        }
        if (dp[a][b] == dp[a-1][b]) {
            a--;
            continue;
        }
        if (dp[a][b] == dp[a][b-1]) {
            b--;
            continue;
        }
    }

    writeln(ans.retro());
}







void scan(T...)(ref T args) {
    import std.stdio : readln;
    import std.algorithm : splitter;
    import std.conv : to;
    import std.range.primitives;

    auto line = readln().splitter();
    foreach (ref arg; args) {
        arg = line.front.to!(typeof(arg));
        line.popFront();
    }
    assert(line.empty);
}


void fillAll(R, T)(ref R arr, T value) {
    static if (is(typeof(arr[] = value))) {
        arr[] = value;
    }
    else {
        foreach (ref e; arr) {
            fillAll(e, value);
        }
    }
}