# Relatively Prime Pairs

medium

You are given a set of all integers from l to r inclusive (r - l is odd).You want to split these numbers into exactly (r-l+1)/2 pairs in such a way that for each pair (i,j), the greates common divisor of i and j is equal to 1. Each pair should appear in exactly one of the pairs. Print the resulting pairs or output that no solution exists.

## Constraints

1 <= l, r, <= 10^8 r-l+1 <= 10^5 and r-l is odd

## Format

### Input

The only line contains two integer l and r.

### Output

If any solution exists, print "YES" in the first line. Each of next (r-l+1)/2 line contains some pair of integers. GCD of each pair of integers should be equal to 1. If there exists no solution print "NO".

## Example

Sample Input

1 8

### Sample Output

YES
1 2
3 4
5 6
7 8