def word_edit_distance(s1, s2):
    a, b = s1.split(), s2.split()
    dp = [[i+j if i*j==0 else 0 for j in range(len(b)+1)] for i in range(len(a)+1)]

    for i in range(1, len(a)+1):
        for j in range(1, len(b)+1):
            if a[i-1] == b[j-1]:
                dp[i][j] = dp[i-1][j-1]
            else:
                dp[i][j] = 1 + min(dp[i-1][j], dp[i][j-1], dp[i-1][j-1])

    return dp[-1][-1]


