Write a python program to sum of all the positive integers that are not bigger than $n($i$.$e$.n)$ and are not divisible by $3(\%30)$ after accepting the value of integer $n$ from the user keyboard. The python program should also account for the case when the user

enters a negative number.

Below are some testing examples

Enter a positive integer:$0$

You have entered an invalid number. Exiting the program.

Enter a positive integer:$-2$

You have entered an invalid number. Exiting the program.

Enter a positive integer:$1$

The sum of the first $1$ positive integers is $1$

Enter a positive integer:$5$

The sum of the first $5$ positive integers is $12$

Enter a positive integer: $10$

The sum of the first $10$ positive integers is $37$