Envío 889

Código

if __name__ == '__main__':
  mat_size = int(input())
  mat = [list(map(int, input().split())) for _ 
  in range(mat_size)]

  accums = [0] * (mat_size * 2 + 2)
  for i, row in enumerate(mat):
    for j, elem in enumerate(row):
      accums[i] += elem
      accums[mat_size + j] += elem
      if i == j:
        accums[-1] += elem
      if mat_size - 1 - j == i:
        accums[-2] += elem
  x0 = accums[0]
  is_magic = all(map(lambda x: x == x0, accums))
  print(['No', 'Yes'][int(is_magic)])