def levenstein(s1, s2):
  table = np.zeros((len(s1) + 1, len(s2) + 1))
  for i in range(len(s1)):
    table[i][0] = i
  for i in range(len(s2)):
    table[0][i] = i
  for i in range(1, len(s1) + 1):
    for j in range(1, len(s2) + 1):
      table[i][j] = min(table[i-1][j] + 1, table[i][j-1] + 1, table[i-1][j-1] + (0 if s1[i-1] == s2[j-1] else 1))
  return table[len(s1)][len(s2)]