import sys
#input = sys.stdin.readline
#input = sys.stdin.buffer.readline #文字列はダメ
#sys.setrecursionlimit(1000000)
import math
import bisect
#import itertools
#import random
from heapq import heapify, heappop, heappush
from collections import defaultdict 
#from collections import deque
import copy #DeepCopy: hoge = [_[:] for _ in hogehoge]
#from functools import lru_cache
#@lru_cache(maxsize=None)
MOD = pow(10,9) + 7
#MOD = 998244353
#dx = [1,0,-1,0]
#dy = [0,1,0,-1]
#dx8 = [1,1,0,-1,-1,-1,0,1]
#dy8 = [0,1,1,1,0,-1,-1,-1]

def main():
    N,K = map(int,input().split())
    N2 = N * 2
    S = [str(input()) for _ in range(N2)]
    C = [list(map(int,input().split())) for _ in range(N2)]

    black = 0
    PQ = []
    for i in range(N2):
        for j in range(N2):
            heappush(PQ,(-C[i][j], i*N2 + j))
            if S[i][j] == '#':
                black += 1

    ans = 0
    used = set([])
    while black > 0:
        v,idx = heappop(PQ)
        ans -= v #負の値が入っている
        black -= 1
        used.add(idx)
        i = idx//N2; j = idx%N2
        ni = i; nj = 2*N-1-j #反対側
        nidx = ni*N2 + nj
        if nidx in used:
            continue
        heappush(PQ,(-C[ni][nj]-K,nidx))
    
    print(ans)


if __name__ == '__main__':
    main()