sum = []


for i in range(len(arr)-2):
    for j in range(len(arr)-2):
        sum.append(arr[i][j]+arr[i][j+1]+arr[i][j+2]+arr[i+1][j+1]+arr[i+2][j]+arr[i+2][j+1]+arr[i+2][j+2])
        
print(max(sum))