CUIT ACM Personal Training 11.27(FM）C - Cupboards

C - Cupboards

Time Limit:2000MS     Memory Limit:262144KB     64bit IO Format:%I64d & %I64u

Description

One foggy Stockholm morning, Karlsson decided to snack on some jam in his friend Lillebror Svantenson's house. Fortunately for Karlsson, there wasn't anybody in his friend's house. Karlsson was not going to be hungry any longer, so he decided to get some food in the house.

Karlsson's gaze immediately fell on n wooden cupboards, standing in the kitchen. He immediately realized that these cupboards have hidden jam stocks. Karlsson began to fly greedily around the kitchen, opening and closing the cupboards' doors, grab and empty all the jars of jam that he could find.

And now all jars of jam are empty, Karlsson has had enough and does not want to leave traces of his stay, so as not to let down his friend. Each of the cupboards has two doors: the left one and the right one. Karlsson remembers that when he rushed to the kitchen, all the cupboards' left doors were in the same position (open or closed), similarly, all the cupboards' right doors were in the same position (open or closed). Karlsson wants the doors to meet this condition as well by the time the family returns. Karlsson does not remember the position of all the left doors, also, he cannot remember the position of all the right doors. Therefore, it does not matter to him in what position will be all left or right doors. It is important to leave all the left doors in the same position, and all the right doors in the same position. For example, all the left doors may be closed, and all the right ones may be open.

Karlsson needs one second to open or close a door of a cupboard. He understands that he has very little time before the family returns, so he wants to know the minimum number of seconds t, in which he is able to bring all the cupboard doors in the required position.

Your task is to write a program that will determine the required number of seconds t.

Input

The first input line contains a single integer n — the number of cupboards in the kitchen (2 ≤ n ≤ 10⁴). Then follow n lines, each containing two integers l_i and r_i (0 ≤ l_i, r_i ≤ 1). Number l_i equals one, if the left door of the i-th cupboard is opened, otherwise number l_i equals zero. Similarly, number r_i equals one, if the right door of the i-th cupboard is opened, otherwise number r_i equals zero.

The numbers in the lines are separated by single spaces.

Output

In the only output line print a single integer t — the minimum number of seconds Karlsson needs to change the doors of all cupboards to the position he needs.

Sample Input

Input

5
0 1
1 0
1 1
0 1
0 1

Output

3

题解：这个题的题目非常长，但是题目是比较简单的，他想让你改变其中的一些值，使得每一列的数字都相同。其实就是计算输入的两列数字中每一列中出现次数少的数的次数之和，比如样例中，第一列1的出现次数最少，第二列0的出现次数最少，那么结果就是第一列1出现的次数和第2列0出现的次数，也就是2+1=3；

所以AC代码如下：

#include <iostream>
using namespace std;
int main()
{
    int n,cnt1=0,cnt2=0,a,b;
    cin>>n;
    for(int i=0;i<n;i++)
    {
        cin>>a>>b;
        if(a==0) cnt1++;
        if(b==0) cnt2++;
    }
    cnt1=min(n-cnt1,cnt1);
    cnt2=min(n-cnt2,cnt2);
    cout<<cnt1+cnt2<<endl;
    return 0;
}