def lcs(X, Y, m, n):
    if (m == 0 or n == 0):
        return 0
    if (X[m - 1] == Y[n - 1]):
        return 1 + lcs(X, Y, m - 1, n - 1)
    else:
        return max(lcs(X, Y, m, n - 1),
                   lcs(X, Y, m - 1, n))
w1 = (input("word 1? "))
w2 = (input("word 2? "))
print(lcs(w1,w2,len(w1),len(w2)))