题目描述 Starting from point $ (0, 0) $ on a plane, we have written all non-negative integers $ 0, 1, 2, \dots $ as shown in the figure. For example, $ 1 $, $ 2 $, and $ 3 $ has been written at points $ (1, 1) $, $ (2, 0) $, and $ (3, 1) $ respectively and this pattern has continued. You are to write a program that reads the coordinates of a point $ (x, y) $, and writes the number (if any) that has been written at that point. $ (x, y) $ coordinates in the input are in the range $ 0 \dots 5000 $. 输入格式 Each line, there is $ x $, and $ y $ representing the coordinates $ (x, y) $ of a point. 输出格式 For each point in the input, write the number written at that point or write No Number if there is none. 输入样例 4 2 输出样例 6