Look and Say Numbers

Given an integer, return a new integer according to the rules below:

• Split the number into groups of two digit numbers. If the number has an odd number of digits, return "invalid".
• For each group of two digit numbers, concatenate the last digit to a new string the same number of times as the value of the first digit.
• Return the result as an integer.

look_and_say(3132) ➞ 111222

# By reading the number digit by digit, you get three "1" and three "2".
# Therefore, you put three ones and three two's together.
# Remember to return an integer.

Examples

look_and_say(95) ➞ 555555555

look_and_say(1213141516171819) ➞ 23456789

look_and_say(120520) ➞ 200

look_and_say(231) ➞ "invalid"

Notes

• Note that the number 0 can be included (see example #3).