## Set .difference() Operation – Hackerrank Solution Python

**.difference()**

The tool *.difference()* returns a set with all the elements from the set that are not in an iterable.

Sometimes the `-`

operator is used in place of the *.difference()* tool, but it only operates on the set of elements in *set*.

Set is immutable to the *.difference()* operation (or the `-`

operation).

>>> s = set("Hacker") >>> print s.difference("Rank") set(['c', 'r', 'e', 'H']) >>> print s.difference(set(['R', 'a', 'n', 'k'])) set(['c', 'r', 'e', 'H']) >>> print s.difference(['R', 'a', 'n', 'k']) set(['c', 'r', 'e', 'H']) >>> print s.difference(enumerate(['R', 'a', 'n', 'k'])) set(['a', 'c', 'r', 'e', 'H', 'k']) >>> print s.difference({"Rank":1}) set(['a', 'c', 'e', 'H', 'k', 'r']) >>> s - set("Rank") set(['H', 'c', 'r', 'e'])

**Task**

Students of District College have a subscription to *English* and *French* newspapers. Some students have subscribed to only the *English* newspaper, some have subscribed to only the *French* newspaper, 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 one set has subscribed to the *French* newspaper. Your task is to find the total number of students who have subscribed to *only English* newspapers.

**Input Format**

The first line contains the number of students who have subscribed to the *English* newspaper.

The second line contains the space separated list of student roll numbers who have subscribed to the *English* newspaper.

The third line contains the number of students who have subscribed to the *French* newspaper.

The fourth line contains the space separated list of student roll numbers who have subscribed to the *French* newspaper.

**Constraints**

0<Total number of students in college<1000

**Output Format**

Output the total number of students who are subscribed to the *English* newspaper *only*.

**Sample Input**

9 1 2 3 4 5 6 7 8 9 9 10 1 2 3 11 21 55 6 8

**Sample Output**

4

**Explanation**

The roll numbers of students who *only* have *English* newspaper subscriptions are:

4,5,7 and 9.

Hence, the total is 4 students.

#Set .difference() Operation - Hackerrank Solution Python Codesagar.in n=int(input()) s=set(map(int,input().split())) m=int(input()) r=set(map(int,input().split())) print(len(s.difference(r))) # Set .difference() Operation - Hackerrank Solution Python codesagar.in

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