描述：

A triangle field is numbered with successive integers in the way shown on the picture below.
 

 

The traveller needs to go from the cell with number M to the cell with number N. The traveller is able to enter the cell through cell edges only, he can not travel from cell to cell through vertices. The number of edges the traveller passes makes the length of the traveller's route.

Write the program to determine the length of the shortest route connecting cells with numbers N and M.

输入：

Input contains two integer numbers M and N in the range from 1 to 1000000000 separated with space(s).

输出：

Output should contain the length of the shortest route.

翻译：如下图所示，一个三角形内被连续的整数以一种方式填满.

旅行者需要从数字M区域走到数字N区域.旅行者只能从数字区域边缘经过，而不能直接通过顶点直接到达.旅行者行走数字边缘的距离计为旅行者的旅程.

编写一个程序确定连接数字M和N的最短长度

输入：输入两个整数N和M（范围为1到1000000000）用空格分隔

输出：输出最短路程的长度.