#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> ii;
typedef vector<ll> vi;
typedef vector<vi> vvi;
typedef vector<ii> vii;

#define x first
#define y second
#define pb push_back
#define eb emplace_back
#define all(v) (v).begin(), (v).end()

const ll m = 100;

void maxCommonSubsequence(string a, string b) {
	ll k = a.size();
	vvi T(k+1, vi(k+1, 0));
	for (ll i = k-1; i >= 0; i--) {
		for (ll j = k-1; j >= 0; j--) {
			if (a[i] == b[j]) {
				T[i][j] = T[i+1][j+1]+1;
			} else {
				T[i][j] = max(T[i+1][j], T[i][j+1]);
			}
		}
	}
	ll i = 0, j = 0;
	while (i < k || j < k) {
		if (i < k && T[i][j] == T[i+1][j]) {
			i++;
		} else if (j < k && T[i][j] == T[i][j+1]) {
			j++;
		} else {
			cout << a[i];
			i++; j++;
		}
	}
}

void run() {
	ll n;
	cin >> n;
	string a, b;
	cin >> a >> b;
	for (ll i = 0; i < n; i += m) {
		maxCommonSubsequence(a.substr(i, min(m, n-i)), b.substr(i, min(m, n-i)));
	}
	cout << endl;
}

signed main() {
    ios_base::sync_with_stdio(false); cin.tie(0);
    run();
    return 0;
}