if __name__ == '__main__':
    n, m = map(int, input().split())
    a = list(input())
    b = list(input())

    dp = [[0] * (m) for _ in range(n)]
    for i in range(0, n):
        for j in range(0, m):
            dp[i][j] = max(dp[i - 1][j], dp[i][j - 1])
            # 找到一个 lcs 中的字符
            if a[i] == b[j]: dp[i][j] = max(1 + dp[i - 1][j - 1], dp[i][j])
    print(dp[-1][-1])