The goal is to find the line in which a word occurs in a given .txt file.
In my code I’ve defined a function and have used with open syntax. When I execute it, all I get is “enter the word you want to find” and when I enter the word, the execution automatically ends

I’ve been cracking my head as to where I went wrong, but couldn’t spot my mistake. I’d be grateful if you can spot the error in the code below.

The following code in Python is what I’ve tried

def find_line(x):
    f=open("practice.txt","r+")
    a=f.read()
    b=f.readlines()
    if(a.find(x)==-1):
        print("word not found!")
    else:
        line_number=1
        for line in b:
            if(line.find(x)==-1):
                line_number+=1
            else:
                print("the word exists in the line,whose number is",line_number)
x=input("enter the word you want to find")       
find_line(x)    

It stopped execution after the word input.