CF922B.Magic Forest
普及/提高-
通过率:0%
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题目描述
Imp is in a magic forest, where xorangles grow (wut?)
A xorangle of order n is such a non-degenerate triangle, that lengths of its sides are integers not exceeding n , and the xor-sum of the lengths is equal to zero. Imp has to count the number of distinct xorangles of order n to get out of the forest.
Formally, for a given integer n you have to find the number of such triples (a,b,c) , that:
- 1<=a<=b<=c<=n ;
, where
denotes the bitwise xor of integers x and y .
- (a,b,c) form a non-degenerate (with strictly positive area) triangle.
输入格式
The only line contains a single integer n (1<=n<=2500) .
输出格式
Print the number of xorangles of order n .
输入输出样例
输入#1
6
输出#1
1
输入#2
10
输出#2
2
说明/提示
The only xorangle in the first sample is (3,5,6) .