303130: CF610A. Pasha and Stick
Memory Limit:256 MB
Time Limit:1 S
Judge Style:Text Compare
Creator:
Submit:0
Solved:0
Description
Pasha and Stick
题意翻译
Pasha有一个正整数长度的木棍n。他想要完成三次切割以获得四个部分。每个部分必须有一些正整数长度,这些长度的总和显然是n。 Pasha喜欢长方形但讨厌正方形,所以他想知道,有多少种方法可以将棍子分成四个部分,这样就可以用这些部分形成一个矩形,但不可能形成正方形。 你的任务是帮助Pasha并计算这些方式的数量。题目描述
Pasha has a wooden stick of some positive integer length $ n $ . He wants to perform exactly three cuts to get four parts of the stick. Each part must have some positive integer length and the sum of these lengths will obviously be $ n $ . Pasha likes rectangles but hates squares, so he wonders, how many ways are there to split a stick into four parts so that it's possible to form a rectangle using these parts, but is impossible to form a square. Your task is to help Pasha and count the number of such ways. Two ways to cut the stick are considered distinct if there exists some integer $ x $ , such that the number of parts of length $ x $ in the first way differ from the number of parts of length $ x $ in the second way.输入输出格式
输入格式
The first line of the input contains a positive integer $ n $ ( $ 1<=n<=2·10^{9} $ ) — the length of Pasha's stick.
输出格式
The output should contain a single integer — the number of ways to split Pasha's stick into four parts of positive integer length so that it's possible to make a rectangle by connecting the ends of these parts, but is impossible to form a square.
输入输出样例
输入样例 #1
6
输出样例 #1
1
输入样例 #2
20
输出样例 #2
4