HackerRank Set .add() problem solution in python | python Question solution

If we want to add a single element to an existing set, we can use the .add() operation.
It adds the element to the set and returns ‘None‘.

Example

>>> s = set('HackerRank')
>>> s.add('H')
>>> print s
set(['a', 'c', 'e', 'H', 'k', 'n', 'r', 'R'])
>>> print s.add('HackerRank')
None
>>> print s
set(['a', 'c', 'e', 'HackerRank', 'H', 'k', 'n', 'r', 'R'])

Task

Apply your knowledge of the .add() operation to help your friend Rupal.

Rupal has a huge collection of country stamps. She decided to count the total number of distinct country stamps in her collection. She asked for your help. You pick the stamps one by one from a stack of  country stamps.

Find the total number of distinct country stamps.

The first line contains an integer , the total number of country stamps.
The next  lines contains the name of the country where the stamp is from.

Constraints

Output the total number of distinct country stamps on a single line.

7
UK
China
USA
France
New Zealand
UK
France 

5

UK and France repeat twice. Hence, the total number of distinct country stamps is  (five).

In this Set .add() problem we need to develop a python program that can read an integer and string input separated with each line. and then we need to print the unique number of countries that given to us on the output screen.

Problem solution in Python 2 programming.

n = int(raw_input())
stamp = set()
for i in range(n):
  stamp.add(raw_input())
print len(stamp)

Problem solution in Python 3 programming.

# Enter your code here. Read input from STDIN. Print output to STDOUT
a = set()
[a.add(input()) for _ in range(int(input()))]
print(len(a))

Problem solution in pypy programming.

n = int(raw_input())
estampas = [raw_input() for i in range(n)]

print len(set(estampas))

Problem solution in pypy3 programming.

# Enter your code here. Read input from STDIN. Print output to STDOUT
num  = int(input())
country = set([])
for i in range(num):
    country.add(input())
print(len(list(country)))