LCS.cpp

#include <bits/stdc++.h>

using namespace std;

#define long long long int

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    string s, t;
    cin >> s >> t;

    int n = s.size(), m = t.size();
    vector<vector<int>> dp(n + 1, vector<int>(m + 1, 0));

    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= m; j++) {
            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);
        }
    }

    string ans = "";
    int i = n, j = m;

    while (i && j) {
        if (dp[i][j] == dp[i - 1][j]) i--;
        else if (dp[i][j] == dp[i][j - 1]) j--;
        else ans += s[--i], j--;
    }

    reverse(ans.begin(), ans.end());
    cout << ans << "\n";
}