NumberFormatException in Kotlin (IntelliJ)

Here is what I am trying to do, I want the user to enter whatever number and it should be displayed, but I am getting this error.
import java.util.*

This is my code

fun main(){
print("Enter your age")
var age = readLine()!!.toInt()
print(age)
}

And the error I am getting is

Enter your age 40
Exception in thread "main" java.lang.NumberFormatException: For input string: " 40"
at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:67)
at java.base/java.lang.Integer.parseInt(Integer.java:654)
at java.base/java.lang.Integer.parseInt(Integer.java:784)
at HelloKt.main(Hello.kt:5)
at HelloKt.main(Hello.kt)

Process finished with exit code 1

>Solution :

You are writing a space in front of the 40 as indicated by the error " 40".

A solution could be is to trim all leading and trailing whitespaces from the readLine, like this:

var age = readLine()!!.trim().toInt()