#!/usr/bin/env python3

n = int(input())
a, b = input(), input()


def lcs(a, b):
    n = len(a)
    dp = [[0] * (n + 1) for _ in range(n + 1)]
    for i, c in enumerate(a):
        for j, d in enumerate(b):
            dp[i + 1][j + 1] = max(
                dp[i][j + 1], dp[i + 1][j], dp[i][j] + (1 if c == d else 0)
            )

    s = []
    i = j = n

    while i > 0 and j > 0:
        if dp[i][j] == dp[i - 1][j - 1] + 1 and a[i - 1] == b[j - 1]:
            s.append(a[i - 1])
            i -= 1
            j -= 1
        elif dp[i][j] == dp[i - 1][j]:
            i -= 1
        else:
            j -= 1

    return "".join(reversed(s))


for i in range(0, n, 10):
    print(lcs(a[i : i + 10], b[i : i + 10]), end="")