Codeforces Round #802 (Div. 2) 1700B. Palindromic Numbers Solution

 Problem Link: https://codeforces.com/contest/1700/problem/B

Solution in Python :

1. test=int(input())
2. while test:
3. test-=1
4. num=int(input())
5. str=int(input())
6. str2=int("1"*num)
7. if str>str2:
8. print(int("1"*(num+1))-str)
9. else:
10. print(int("9"*num)-str)