Problem:
Score : 300 points

Problem Statement

A sequence a_1,a_2,... ,a_n is said to be /\/\/\/ when the following conditions are satisfied:

For each i = 1,2,..., n-2, a_i = a_{i+2}.

Exactly two different numbers appear in the sequence.

You are given a sequence v_1,v_2,...,v_n whose length is even.
We would like to make this sequence /\/\/\/ by replacing some of its elements.
Find the minimum number of elements that needs to be replaced.

Constraints

2 \leq n \leq 10^5

n is even.

1 \leq v_i \leq 10^5

v_i is an integer.

Input

Input is given from Standard Input in the following format:

n
v_1 v_2 ... v_n

Output

Print the minimum number of elements that needs to be replaced.

Sample Input 1

4
3 1 3 2

Sample Output 1

1

The sequence 3,1,3,2 is not /\/\/\/, but we can make it /\/\/\/ by replacing one of its elements: for example, replace the fourth element to make it 3,1,3,1.

Sample Input 2

6
105 119 105 119 105 119

Sample Output 2

0

The sequence 105,119,105,119,105,119 is /\/\/\/.

Sample Input 3

4
1 1 1 1

Sample Output 3

2

The elements of the sequence 1,1,1,1 are all the same, so it is not /\/\/\/.

Solution in C++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include<bits/stdc++.h>

using namespace std;

const int maxn=1e6;

int n;

int a[maxn],b[maxn];

int mx[2],mw[2];

int main() {
	scanf("%d",&n);
	for (int l=1;l<=n;l++) {
		int wy;
		scanf("%d",&wy);
		if (l&1) a[wy]++;
		else b[wy]++;
	}
	for (int l=1;l<=n;l++) {
		int wyx=a[l],wyw=l;
		for (int j=0;j<=1;j++) {
			if (wyx>mx[j]) {
				swap(wyx,mx[j]);
				swap(wyw,mw[j]);
			}
		}
	}
	int ans=1e9;
	for (int l=1;l<=1e5+10;l++) {
		int wy;
		if (a[l]==mx[0]) wy=mx[1];
		else wy=mx[0];
	//	cout<<l<<" "<<wy<<" ";
		wy=n-wy-b[l];
	//	cout<<b[l]<<" "<<wy<<endl;
		ans=min(ans,wy);
	}
	printf("%d\n",ans);
}