# HackerRank Set .union() Operation solution in python | python practice problems for beginners with solutions

 In this Set .union() operation problem we need to develop a python program that can read four lines of input and then we need to print the total number of students who have at least one subscription on the output screen.

.union()

The .union() operator returns the union of a set and the set of elements in an iterable.
Sometimes, the | operator is used in place of .union() operator, but it operates only on the set of elements in set.
Set is immutable to the .union() operation (or | operation).

Example

``>>> s = set("Hacker")>>> print s.union("Rank")set(['a', 'R', 'c', 'r', 'e', 'H', 'k', 'n'])>>> print s.union(set(['R', 'a', 'n', 'k']))set(['a', 'R', 'c', 'r', 'e', 'H', 'k', 'n'])>>> print s.union(['R', 'a', 'n', 'k'])set(['a', 'R', 'c', 'r', 'e', 'H', 'k', 'n'])>>> print s.union(enumerate(['R', 'a', 'n', 'k']))set(['a', 'c', 'r', 'e', (1, 'a'), (2, 'n'), 'H', 'k', (3, 'k'), (0, 'R')])>>> print s.union({"Rank":1})set(['a', 'c', 'r', 'e', 'H', 'k', 'Rank'])>>> s | set("Rank")set(['a', 'R', 'c', 'r', 'e', 'H', 'k', 'n'])``

The students of District College have subscriptions to English and French newspapers. Some students have subscribed only to English, some have subscribed to only French and some have subscribed to both newspapers.

You are given two sets of student roll numbers. One set has subscribed to the English newspaper, and the other set is subscribed to the French newspaper. The same student could be in both sets. Your task is to find the total number of students who have subscribed to at least one newspaper.

Input Format

The first line contains an integer, , the number of students who have subscribed to the English newspaper.
The second line contains  space separated roll numbers of those students.
The third line contains , the number of students who have subscribed to the French newspaper.
The fourth line contains  space separated roll numbers of those students.

Constraints

Output Format

Output the total number of students who have at least one subscription.

Sample Input

``91 2 3 4 5 6 7 8 9910 1 2 3 11 21 55 6 8``

Sample Output

``13``

Explanation

Roll numbers of students who have at least one subscription:
and . Roll numbers:  and  are in both sets so they are only counted once.
Hence, the total is  students.

## Problem solution in Python 2 programming.

`eng = set()fre = set()n = raw_input()for i in raw_input().split(' '):  eng.add(i)m = raw_input()for i in raw_input().split(' '):  fre.add(i)sol = eng.union(fre)print len(sol)`

## Problem solution in Python 3 programming.

`# Enter your code here. Read input from STDIN. Print output to STDOUTn = int(input())l = list(input().split())m = int(input())k = list(input().split())s1 = set(l)s2 = set(k)print(len(s1.union(s2)))`

### Problem solution in pypy programming.

`# Enter your code here. Read input from STDIN. Print output to STDOUTn = input()s = set(map(int, raw_input().split())) m = input()t = set(map(int, raw_input().split()))print len(s.union(t))`

### Problem solution in pypy3 programming.

`n = int(input())A = set(map(int, input().split()))m = int(input())B = set(map(int, input().split()))ans = A.union(B)print(len(ans))`