Problems
Rectangle
Rectangle
Four positive integers a, b, c, d are given. Find the sum of the given numbers if there exists a rectangle with side lengths a, b, c, d. Print "No" otherwise.
Input data
Four positive integers a, b, c, d, each no more than 10^9.
Output data
If the rectangle exists, print the sum of all numbers. Otherwise print "No".
Examples
Input example #1
7 4 4 7
Output example #1
22
Input example #2
9 9 9 6
Output example #2
No