Buggy python submission (verdict: Time Limit Exceeded):
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[1]*(W) for i in range(H)]
B =[[1]*(H) for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i][k-j-1]=a
            A[i][k]=a
            a = 0
            k = k+1
    for j in range(a):
                A[i][k-j-1]=a
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i][k-j-1]=a
            B[i][k] = 0
            a = 0
            k = k+1
    for j in range(a):
                B[i][k-j-1]= a
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)
        

Fixed submission:
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[1]*(W) for i in range(H)]
B =[[1]*(H) for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i][k-j-1]=a
            A[i][k]=a
            a = 0
            k = k+1
    for j in range(a):
                A[i][k-j-1]=a
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i][k-j-1]=a
            B[i][k] = 0
            a = 0
            k = k+1
    for j in range(a):
                B[i][k-j-1]= a
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)

Buggy python submission (verdict: Runtime Error):
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[[1]*(W) for i in range(H)]
B =[[] for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i][k-j-1]=a
            A[i][k]=a
            a = 0
            k = k+1
    for j in range(a):
                A[i][k-j-1]=a
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i][k-j-1]=a
            B[i][k] = 0
            a = 0
            k = k+1
    for j in range(a):
                B[i][k-j-1]= a
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)
        

Fixed submission:
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[1]*(W) for i in range(H)]
B =[[1]*(H) for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i][k-j-1]=a
            A[i][k]=a
            a = 0
            k = k+1
    for j in range(a):
                A[i][k-j-1]=a
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i][k-j-1]=a
            B[i][k] = 0
            a = 0
            k = k+1
    for j in range(a):
                B[i][k-j-1]= a
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)

Buggy python submission (verdict: Time Limit Exceeded):
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[] for i in range(H)]
B =[[] for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i].append(a)
            A[i].append(0)
            a = 0
            k = k+1
    for j in range(a):
                A[i].append(a)
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i].append(a)
            B[i].append(0)
            a = 0
            k = k+1
    for j in range(a):
                B[i].append(a)
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)
        

Fixed submission:
H,W = map(int,input().split())
List=[input() for i in range(H)]
A =[[1]*(W) for i in range(H)]
B =[[1]*(H) for i in range(W)]
for i in range(H):
    k = 0
    a = 0
    while k < W:
        if List[i][k]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                A[i][k-j-1]=a
            A[i][k]=a
            a = 0
            k = k+1
    for j in range(a):
                A[i][k-j-1]=a
for i in range(W):
    k = 0
    a = 0
    while k < H:
        if List[k][i]==".":
            a += 1
            k = k+1
        else:
            for j in range(a):
                B[i][k-j-1]=a
            B[i][k] = 0
            a = 0
            k = k+1
    for j in range(a):
                B[i][k-j-1]= a
max = 0
for i in range(H):
    for j in range(W):
        if max < A[i][j] + B[j][i]:
            max = A[i][j] + B[j][i]
print(max-1)