from random import randint
from pprint import pprint

matrix_size = None

while matrix_size not in (2, 3, 4, 5):
    try:
        matrix_size = int(input('Input size of matrix: '))
        if matrix_size not in (2, 3, 4, 5):
            raise ValueError
    except ValueError:
        print('Give correct data for size of matrix (integer number from 2 to 5')

matrix = [[0 for i in range(matrix_size)] for j in range(matrix_size)]

command_chose = None

while command_chose not in (1, 2):
    try:
        command_chose = int(input('1.Ввести числа самостоятельно\n2.Заполнить автоматически\nYou answer: '))
    except ValueError:
        print('Give correct data for choose the command')

if command_chose == 1:
    for i in range(matrix_size):
        for j in range(matrix_size):
            number = None
            while not isinstance(number, int) or number > 100 or number < 0:
                try:
                    number = int(input(f'Введите число от 0 до 100 для {i} строки и {j} колонки матрицы: '))
                except ValueError:
                    print('Неверные данные (type of integer and range from 1 to 100')

            matrix[i][j] = int(number)

elif command_chose == 2:
    for i in range(matrix_size):
        for j in range(matrix_size):
            matrix[i][j] = randint(1, 100)

diagonal_elements = [matrix[i][i] for i in range(matrix_size) for j in range(matrix_size) if i == j]
diagonal_elements.sort()

pprint(matrix)
print(diagonal_elements)

for i in range(matrix_size):
    for j in range(matrix_size):
        if i == j:
            matrix[i][j] = diagonal_elements[i]
        else:
            matrix[i][j] *= -1

pprint(matrix)

n_diag_max = None

available_max = [i for i in range(matrix_size)]

while n_diag_max not in available_max:
    try:
        n_diag_max = int(input('Get number n-maximum on main diag of matrix: '))
        n_diag_max -= 1
    except ValueError:
        print('Invalid data, please try again')

print(f'N maximum is {diagonal_elements[n_diag_max]}')