Ответ:

from random import randint  

n = int(input('size: '))

m = [[randint(0, 100) for _ in range(n)] for _ in range(n)]  

print('матрица:')  

c = []  

for r in range(n):

 print(*m[r])

 c.append(m[r][0])

print('макс-элемент:', max(map(max, m)))

rows = [sum(row) for row in m]

print('сумма элемнтов:', sum(rows))