mas = [[5, 3, 12], [13,7, 7], [21,6,8]]
a = 0
for i in range(len(mas)):
for j in range(len(mas[i])):
a = a + mas[i][j]
print(a)
mas = [[5, 3, 12], [13,7, 7], [21,6,8]]
a = 0
for i in range(len(mas)):
for j in range(len(mas[i])):
a = a + mas[i][j]
print(a)