有一种策略...

最新推荐文章于 2020-01-20 14:25:50 发布

原创最新推荐文章于 2020-01-20 14:25:50 发布 · 342 阅读

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本文探讨了一种求最小值的策略，类似于基本不等式的应用，通过实例介绍了一个寻找最短路径的问题，给出了一段C++代码实现。

啊不知道是什么策略啊= =
不知道怎么讲啊
用了好多次
就是求最小值的时候越接近越越对？
嗯呢类似基本不等式的感觉诶…….方差月小越好类似这种

A few years ago Sajjad left his school and register to another one due to security reasons. Now he wishes to find Amir, one of his schoolmates and good friends.

There are n schools numerated from 1 to n. One can travel between each pair of them, to do so, he needs to buy a ticket. The ticker between schools i and j costs and can be used multiple times. Help Sajjad to find the minimum cost he needs to pay for tickets to visit all schools. He can start and finish in any school.

Input

The first line contains a single integer n (1 ≤ n ≤ 105) — the number of schools.

Output

Print single integer: the minimum cost of tickets needed to visit all schools.

Example
Input

2

Output

0

Input

10

Output

4

Note

In the first example we can buy a ticket between the schools that costs .

使1与n搭配，2与n - 1搭

#include<iostream>
using namespace std;
int main()
{
    int n;
    while (cin >> n){
        cout << (n - 1) / 2 << endl;
    }
    return 0;
}

还有好几道呢= =
记住好啦 = =以后肯定会有的