Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1
            
        else:
            U[i][j] = 0
            L[i][j] = 0

        ri = H-i-1
        rj = W-j-1
        if S[ri][rj] == ".":
            if i != 0:
                D[ri][rj] = D[ri+1][rj]+1
            else:
                D[ri][rj] = 1
            if j != 0:
                R[ri][rj] = R[ri][rj+1]+1
            else:
                R[ri][rj] = 1
        else:
            D[ri][rj] = 0
            R[ri][rj] = 0


ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)

Fixed submission:
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1
            
        else:
            U[i][j] = 0
            L[i][j] = 0

        ri = H-i-1
        rj = W-j-1
        if S[ri][rj] == ".":
            if i != 0:
                D[ri][rj] = D[ri+1][rj]+1
            else:
                D[ri][rj] = 1
            if j != 0:
                R[ri][rj] = R[ri][rj+1]+1
            else:
                R[ri][rj] = 1
        else:
            D[ri][rj] = 0
            R[ri][rj] = 0


ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1               
            
        else:
            U[i][j] = 0
            L[i][j] = 0

        if S[H-i-1][W-j-1] == ".":
            if i != 0:
                D[H-i-1][W-j-1] = D[H-i][W-j-1]+1
            else:
                D[H-i-1][W-j-1] = 1
            if j != 0:
                R[H-i-1][W-j-1] = R[H-i-1][W-j]+1
            else:
                R[H-i-1][W-j-1] = 1 
        else:
            D[H-i-1][W-j-1] = 0
            R[H-i-1][W-j-1] = 0        


ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)

Fixed submission:
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1
            
        else:
            U[i][j] = 0
            L[i][j] = 0

        ri = H-i-1
        rj = W-j-1
        if S[ri][rj] == ".":
            if i != 0:
                D[ri][rj] = D[ri+1][rj]+1
            else:
                D[ri][rj] = 1
            if j != 0:
                R[ri][rj] = R[ri][rj+1]+1
            else:
                R[ri][rj] = 1
        else:
            D[ri][rj] = 0
            R[ri][rj] = 0


ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)

Buggy python submission (verdict: Time Limit Exceeded):
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1               
            
        else:
            U[i][j] = 0
            L[i][j] = 0
        
for i in range(H-1,-1,-1):
    for j in range(W-1,-1,-1):
        if S[i][j] == ".":
            if i != H-1:
                D[i][j] = D[i+1][j]+1
            else:
                D[i][j] = 1
            if j != W-1:
                R[i][j] = R[i][j+1]+1
            else:
                R[i][j] = 1      
            
        else:
            D[i][j] = 0
            R[i][j] = 0

ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)

Fixed submission:
H,W = list(map(int,input().split()))

S = [input() for i in range(H)]

L,R,U,D = [[[0]*W for i in range(H)] for i in range(4)]

for i in range(H):
    for j in range(W):
        if S[i][j] == ".":
            if i != 0:
                U[i][j] = U[i-1][j]+1
            else:
                U[i][j] = 1
            if j != 0:
                L[i][j] = L[i][j-1]+1
            else:
                L[i][j] = 1
            
        else:
            U[i][j] = 0
            L[i][j] = 0

        ri = H-i-1
        rj = W-j-1
        if S[ri][rj] == ".":
            if i != 0:
                D[ri][rj] = D[ri+1][rj]+1
            else:
                D[ri][rj] = 1
            if j != 0:
                R[ri][rj] = R[ri][rj+1]+1
            else:
                R[ri][rj] = 1
        else:
            D[ri][rj] = 0
            R[ri][rj] = 0


ans = 0
for i in range(H):
    for j in range(W):
        ans = max(ans,L[i][j]+R[i][j]+U[i][j]+D[i][j]-3)

print(ans)