C. Count Triangles

最新推荐文章于 2023-04-14 21:24:50 发布

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最新推荐文章于 2023-04-14 21:24:50 发布

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该问题要求计算在给定整数限制A, B, C, D之间，有多少种不同的非退化三角形（x, y, z）组合，其中A <= x <= B <= y <= C <= z <= D。输入包含四个整数A, B, C, D，输出为符合条件的三角形数量。例子展示了不同A, B, C, D值下的三角形计数情况。" 121679627,11417367,STM32移植uCOSIII到HAL库实战指南,"['STM32开发', '嵌入式系统', 'RTOS', 'HAL库', '单片机编程']

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链接：https://codeforces.com/contest/1355/problem/C

Like any unknown mathematician, Yuri has favourite numbers: AA, BB, CC, and DD, where A≤B≤C≤DA≤B≤C≤D. Yuri also likes triangles and once he thought: how many non-degenerate triangles with integer sides xx, yy, and zz exist, such that A≤x≤B≤y≤C≤z≤DA≤x≤B≤y≤C≤z≤D holds?

Yuri is preparing problems for a new contest now, so he is very busy. That's why he asked you to calculate the number of triangles with described property.

The triangle is called non-degenerate if and only if its vertices are not collinear.

Input

The first line contains four integers: AA, BB, CC and DD (1≤A≤B≤C≤D≤5⋅1051≤A≤B≤C≤D≤5⋅105) — Yuri's favourite numbers.

Output

Print the number of non-degenerate triangles with integer sides xx, yy, and zz such that the inequality A≤x≤B≤y≤C≤z≤DA≤x≤B≤y≤C≤z≤D holds.

Examples

input

Copy

1 2 3 4

output

Copy

input

Copy

1 2 2 5

output

Copy

input

Copy

500000 500000 500000 500000

output

Copy

Note

In the first example Yuri can make up triangles with sides (1,3,3)(1,3,3), (2,2,3)(2,2,3), (2,3,3)(2,3,3) and (2,3,4)(2,3,4).

In the second example Yuri can make up triangles with sides (1,2,2)(1,2,2), (2,2,2)(2,2,2) and (2,2,3)(2,2,3).

In the third example Yuri can make up only one equilateral triangle with sides equal to 5⋅1055⋅105.

qlsNB！！！

代码：

#include <algorithm>
#include <bitset>
#include <cctype>
#include <cerrno>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <iomanip>
#include <ios>
#include<iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <vector>
#include <cwchar>
#include <cwctype>
#define ll long long
#define rep(i,a,n) for(int i=a;i<=n;i++)
using namespace std;
ll n,m,t,k,s,z,y,l,r,ans;
ll a,b,c,d;
int main()
{
	cin>>a>>b>>c>>d;
	ans=0;
	for(ll i=max(a+b,c+1);i<=b+c;i++)
	{
		l=max(a,i-c);
		r=min(b,i-b);
		if(l<=r)
		{
			ans+=(r-l+1)*(min(i-1,d)-c+1);
		}
	}
	cout<<ans;
}