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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<ll, ll> l_l;
typedef pair<int , int> i_i;
typedef vector<ll> vel;
typedef vector<int> vei;
typedef vector<char> vec;
typedef vector<bool> veb;
typedef vector<string> ves;
typedef vector<vector<ll>> ve_vel;
typedef vector<vector<int>> ve_vei;
typedef vector<vector<char>> ve_vec;
typedef vector<vector<bool>> ve_veb;
typedef vector<vector<string>> ve_ves;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<(int)(n);i++)
#define rep2(i,n) for(int i=2;i<(int)(n);i++)
#define repk(i,k,n) for(int i=k;i<(int)(n);i++)
#define fs first
#define sc second
#define pub push_back
#define puf push_front
#define pob pop_back
#define all(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define maxel(a) *max_element(all(a))
#define minel(a) *min_element(all(a))
#define acc accumulate
#define EPS (1e-7)
#define INF (1e9)
#define PI (acos(-1))
#define mod (1000000007)
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<typename T> void remove(T & vector, unsigned int index){vector.erase(vector.begin() + index);}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);

    int N; cin >> N;
    vei v(N); rep(i,N) cin >> v[i];

    vei check(100005, 0), check2(100005, 0);

    bool same = true;
    rep(i,N-1) if(v[i] != v[i+1]) same = false;
    if(same) {cout << N/2 << endl; return 0;}

    rep(i,N) {
        if(i % 2 == 0) check[ v[i] ]++;
        else check2[ v[i] ]++;
    }
    
    int max1 = maxel(check);
    int max2 = maxel(check2);

    auto it = lower_bound(all(check), max1);
    auto it2 = lower_bound(all(check2), max2);
    
    int index = *it;
    int index2 = *it2;

    if(index != index2) {
        int change = acc(all(check), 0) - max1;
        int change2 = acc(all(check2), 0) - max2;
        cout << change + change2 << endl;
    }
    else {
        if(max1 > max2) {
            int max0 = 0;
            int change = acc(all(check), 0) - max1;
            for(int i = 0; i <= 100000; i++) {
                if(i == index2+1) continue;
                else {int temp = check2[i]; max0 = max(max0, temp);} 
            }
            int change2 = acc(all(check2), 0) - max0;
            cout << change + change2 << endl;
        }
        if(max1 < max2) {
            int max0 = 0;
            int change2 = acc(all(check2), 0) - max2;
            for(int i = 0; i <= 100000; i++) {
                if(i == index+1) continue;
                else {int temp = check[i]; max0 = max(max0, temp);} 
            }
            int change = acc(all(check), 0) - max0;
            cout << change + change2 << endl;
        }
        if(max1 == max2) {
            sort(rall(check)); sort(rall(check2));
            int max01 = check[1]; int max02 = check[1];
            if(max01 > max02) {
                int change = acc(all(check), 0) - max01;
                int change2 = acc(all(check2), 0) - max2;
                cout << change + change2 << endl;
            }
            if(max01 < max02) {
                int change = acc(all(check),0) - max1;
                int change2 = acc(all(check2),0) - max02;
                cout << change + change2 << endl;
            }
            if(max01 == max02) {
                int change = acc(all(check),0) - max01;
                int change2 = acc(all(check2),0) - max2;
                cout << change + change2  << max01 << max02 << max1 << max2<<acc(all(check2),0)<<endl;
            }
        
        }
    }

}