Problem:
We have a canvas divided into a grid with H rows and W columns. The square at the i-th row from the top and the j-th column from the left is represented as (i, j).   Initially, all the squares are white. square1001 wants to draw a picture with black paint. His specific objective is to make Square (i, j) black when s_{i, j}= `#`, and to make Square (i, j) white when s_{i, j}= `.`.   However, since he is not a good painter, he can only choose two squares that are horizontally or vertically adjacent and paint those squares black, for some number of times (possibly zero). He may choose squares that are already painted black, in which case the color of those squares remain black.   Determine if square1001 can achieve his objective.

Incorrect submission (verdict: Wrong Answer):
n = input().split()

n = [int(n[0]), int(n[1])]
H = n[0]
W=n[1]

s = [list(map(str, input().split())) for i in range(H)]
print(s[0][0][1])
c = True
for i in range(H):
    for j in range(W):
        if(s[i][0][j] == '#'):
            if(i == 0):
                if(j == 0):
                    if(s[i + 1][0][j] == '.' and s[i][0][j + 1] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i+1][0][j ] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
                else:
                     if(s[i + 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
            elif(i == H - 1):
                if(j == 0):
                    if(s[i - 1][0][j] == '.' and s[i][0][j +1] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i-1][0][j] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
                else:
                     if(s[i - 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
            else:
                if(j == 0):
                    if(s[i - 1][0][j] == '.' and s[i][0][j +1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i-1][0][j] == '.' and s[i][0][j-1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                else:
                     if(s[i - 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                
    
if(c):
    print("Yes")
else:
    print("No")

Fixed, accepted submission:
n = input().split()

n = [int(n[0]), int(n[1])]
H = n[0]
W=n[1]

s = [list(map(str, input().split())) for i in range(H)]

c = True
for i in range(H):
    for j in range(W):
        if(s[i][0][j] == '#'):
            if(i == 0):
                if(j == 0):
                    if(s[i + 1][0][j] == '.' and s[i][0][j + 1] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i+1][0][j ] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
                else:
                     if(s[i + 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
            elif(i == H - 1):
                if(j == 0):
                    if(s[i - 1][0][j] == '.' and s[i][0][j +1] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i-1][0][j] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
                else:
                     if(s[i - 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.'):
                        c = False
                        break
            else:
                if(j == 0):
                    if(s[i - 1][0][j] == '.' and s[i][0][j +1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                elif(j == W - 1):
                    if(s[i-1][0][j] == '.' and s[i][0][j-1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                else:
                     if(s[i - 1][0][j] == '.' and s[i][0][j + 1] == '.' and s[i][0][j-1] == '.' and s[i + 1][0][j] == '.'):
                        c = False
                        break
                
    
if(c):
    print("Yes")
else:
    print("No")