The input is a natural number n — the number of rows and columns in the square matrix. Next, the elements of the matrix are entered line by line with a space. Draw the maximum element below the main diagonal. The elements of the main diagonal are also taken into account.

import numpy as np

def max_under_diagonal(a):
    n = len(a)
    max_elem = a[0][1]
    for i in range(n):
        for j in range(i+1, n):
            max_elem = max(max_elem, a[i][j])
    return max_elem

a = np.random.randint(0, 10, size=(3,3))
a = np.array([[1,2,3],[4,5,6],[7,8,9]])
print(max_under_diagonal(a))