How to take a simple integer matrix as input in python3

Question

I want to take a simple matrix as input in a 2-D array, but get a Runtime Error - NZEC error.
Matrix -

1 2  
3 4  

my input code -

for i in range(2):
    a[i]=[int(i) for i in input().split()]
print(a)

Answer 1

1. You are using i as the loop variable and the list comprehension variable at the same time

2. You have not declared a (visibly). Declare a = [] and use list.append.

---

Try this:

a = []
for _ in range(2):
    a.append([int(i) for i in input().split()])

Declare a to be empty initially. Then call a.append to append new sublists to your list.