a = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
for row in a:
print(row[0])
1 4 7
for row in a:
for element in row:
print(element)
1 2 3 4 5 6 7 8 9
for i in range(3):
print(a[i][i])
1 5 9
for i in range(3):
print(f'The {i + 1}-th diagonal element is: {a[i][i]}')
The 1-th diagonal element is: 1 The 2-th diagonal element is: 5 The 3-th diagonal element is: 9