def lss(str1, str2):
    max_len = max(len(str1), len(str2))
    arr = [[0 for _ in range(max_len)] for _ in range(max_len)]
    maxx = 0
    for i2 in range(len(str2)):
        for i1 in range(len(str1)):
            if str1[i1] == str2[i2]:
                if i1 > 0 and i2 > 0:
                    val = arr[i1-1][i2-1]
                    if val + 1 > maxx:
                        maxx =  val + 1
                    arr[i1][i2] = val + 1

    print(maxx)

# lss("yellxy", "fellur")

def lss_2(str1, str2):
    max_len = max(len(str1), len(str2))
    arr = [[0 for _ in range(max_len)] for _ in range(max_len)]
    maxx = 0
    for i2 in range(len(str2)):
        for i1 in range(len(str1)):
            if str1[i1] == str2[i2]:
                if i1 > 0 and i2 > 0:
                    up = arr[i1][i2-1]
                    left = arr[i1-1][i2]
                    val = max(up, left)
                    # val = arr[i1-1][i2-1]
                    if val + 1 > maxx:
                        maxx =  val + 1
                    arr[i1][i2] = val + 1
            else:
                up = arr[i1][i2-1]
                left = arr[i1-1][i2]
                arr[i1][i2] = max(up, left)
    print(maxx)

# lss_2("follow", "yellow") #5
# lss_2("follow", "yelljw") #4