from __future__ import print_function

class EditDistance:

def __init__(self):

self.__prepare__()

def __prepare__(self, N = 0, M = 0):

self.dp = [[-1 for y in range(0,M)] for x in range(0,N)]

def __solveDP(self, x, y):

if (x==-1):

return y+1

elif (y==-1):

return x+1

elif (self.dp[x][y]>-1):

return self.dp[x][y]

else:

if (self.A[x]==self.B[y]):

self.dp[x][y] = self.__solveDP(x-1,y-1)

else:

self.dp[x][y] = 1+min(self.__solveDP(x,y-1), self.__solveDP(x-1,y), self.__solveDP(x-1,y-1))

return self.dp[x][y]

def solve(self, A, B):

if isinstance(A,bytes):

A = A.decode('ascii')

if isinstance(B,bytes):

B = B.decode('ascii')

self.A = str(A)

self.B = str(B)

self.__prepare__(len(A), len(B))

return self.__solveDP(len(A)-1, len(B)-1)