if __name__=="__main__":
    n,m = [int(x) for x in input().split()]
    s1=list(input())
    s2=list(input())

    dp = [[0 for x in range(0,m+1)] for x in range(0,n+1)]

    for i in range(1,n+1):
        for j in range(1,m+1):
            if s1[i-1]==s2[j-1]:
                dp[i][j]=max(dp[i][j-1],dp[i-1][j])
                dp[i][j]=max(dp[i][j], dp[i-1][j-1]+1)
            else:
                dp[i][j]=max(dp[i][j-1],dp[i-1][j])

    print(dp[n][m])