INPUT : 

print("\treplace string")

a="balaji is a class topper"

b='''sanjay will always play games in mobile 

phone but he is a slow learner'''

print(a.replace("class topper","avarage student"))

print(b.replace("slow learner","class topper"))

OUTPUT :

        replace string

balaji is a avarage student

sanjay will always play games in mobile 

phone but he is a class topper