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: Runtime Error)

#include <bits/stdc++.h> 
#define rep(i,n) for (int i = 0; i < (n); ++i)
using ll =long long;
using namespace std;
using Graph=vector<vector<int>>;
using Field=vector<string>;
using P =pair<int,int>;

const ll mod=1000000007;
const int dx[]={0,1,0,-1};
const int dy[]={1,0,-1,0};

int main(){
    int n;
    cin>>n;
    vector<int> v(n);
    rep(i,n)cin>>v[i];
    int a[10001]={};
    int b[10001]={};
    rep(i,n){
        if(i%2==0)a[v[i]]++;
        else b[v[i]]++;
    }
    int maxa[2]={},maxb[2]={};
    int indexa[2]={},indexb[2]={};
    rep(i,10001){
        if(a[i]>maxa[0]){
            maxa[0]=a[i];
            indexa[0]=i;
        }else if(a[i]>maxa[1]){
            maxa[1]=a[i];
            indexa[1]=i;
        }
        if(b[i]>maxb[0]){
            maxb[0]=b[i];
            indexb[0]=i;
        }else if(b[i]>maxb[1]){
            maxb[1]=b[i];
            indexb[1]=i;
        }
    }
    if(maxa[0]==n/2&&maxb[0]==n/2){
        if(indexa[0]==indexb[0]){
            cout<<n/2<<endl;
        }else{
            cout<<0<<endl;
        }
    }else{
        if(indexa[0]==indexb[0]){
            cout<<min(n-maxa[0]-maxb[1],n-maxa[1]-maxb[0])<<endl;
        }else{
            cout<<(n-maxa[0]-maxb[0])<<endl;
        }
    }
    return 0;
}