Max Sum of Diagonal
n = int ( input ()) matrix = [ list ( map ( int , input ().split())) for _ in range (n)] main_diagonals = [ 0 ] * ( 2 * n - 1 ) anti_diagonals = [ 0 ] * ( 2 * n - 1 ) for i in range (n): for j in range (n): val = matrix[i][j] main_diagonals[i - j + n - 1 ] += val anti_diagonals[i + j] += val max_main = max (main_diagonals) max_anti = max (anti_diagonals) print ( max (max_main, max_anti))