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 "\textbf{No}" otherwise. \InputFile Four positive integers $a, b, c, d$, each no more than $10^9$. \OutputFile If the rectangle exists, print the sum of all numbers. Otherwise print "\textbf{No}".