Count and Say

Problem statement

Start a sequence with the string 1. To produce the next term, read the previous term from left to right in maximal runs of equal digits. For each run, append its length in decimal followed by the repeated digit. For example, 1211 becomes 111221 because its runs are one 1, one 2, and two 1s. Find the nth term.

Input format

One integer n.

Output format

Print the nth term as a string of digits.

Constraints

1 <= n <= 20.

Sample input

4

Sample output

1211