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: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <stdbool.h>
typedef long long ll;
#define rep(i,n) for(ll i=0; i<(ll)(n); i++)
#define max(l,r) ((l)>(r)?l:r)
#define min(l,r) ((l)<(r)?l:r)
#define swap(l,r) {ll tp=l;l=r;r=tp;}
const ll MOD = 1000000007;
int upcmpii(const void *a, const void *b){
    return (*(int*)a == *(int*)b ? 0 : (*(int*)a > *(int*)b ? 1 : -1));
}
void sort_ui(int *a, int n){ qsort(a, n, sizeof(int), upcmpii);}

int main(){
    int n;
    scanf("%d", &n);
    int v[101010];
    rep(i, n) scanf("%d", v+i);

    int oc[101010] = {0}, ec[101010] = {0};
    rep(i, n){
        if(i % 2 == 0) oc[v[i]]++;
        else ec[v[i]]++;
    }
    int val[2] = {0}, cnt[2] = {0};
    rep(i, 100001){
        if(oc[i] == 0) continue;
        if(oc[i] > cnt[1]){
            cnt[1] = oc[i];
            val[1] = i;
        }
    }
    rep(i, 100001){
        if(ec[i] == 0) continue;
        if(ec[i] > cnt[0]){
            cnt[0] = ec[i];
            val[0] = i;
        }
    }

    ll ans = 0;
    if(val[0] != val[1]){
        ans = n - cnt[0] - cnt[1];
    }else{
        int vals[2] = {0}, cnts[2] = {0};
        rep(i, 100001){
            if(oc[i] == 0 || i == val[1]) continue;
            if(oc[i] > cnts[1]){
                cnts[1] = oc[i];
                vals[1] = i;
            }
        }
        rep(i, 100001){
            if(ec[i] == 0 || i == val[0]) continue;
            if(ec[i] > cnts[0]){
                cnts[0] = ec[i];
                vals[0] = i;
            }
        }
        ans = n - max(cnt[0]+cnts[1], cnt[1]+cnts[0]);
    }

    printf("%lld", ans);
}