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: Accepted)

#include<bits/stdc++.h>
using namespace std;

#define fi first
#define se second
#define be begin
#define en end
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define ALL(a) (a).be() , (a).en()
#define REP(i,n) for(int (i)=0;(i)<(n);(i)++)        //repeat n times
#define REP2(i,s,n) for(int (i)=(s);(i)<(n);(i)++)   //repeat from s to n 
#define REPD(i,n) for(int (i)=(n);(i)>=0;(i)--)      //repeat from n to 0
#define REPD2(i,s,e) for(int (i)=(s);(i)>=(e);(i)--) //repeat from s to e
#define RANGE(i,v) for(auto &(i):v)                  //repeat range
#define ASIZE(a) (sizeof(a) / sizeof(a[0]))          //array size

using LL = long long;

template<typename T1,typename T2> using P = pair< T1, T2 >;
using Pii = P<int,int>;
using Pll = P<LL,LL>;
using Pdd = P<double,double>;
using Psi = P<string,double>;

template<typename T> using V = vector< T >;
using Vi = V<int>;
using Vll = V<LL>;
using Vs = V<string>;

template<typename T1,typename T2> using M = map< T1, T2>;
using Mii = M<int, int>;
using Msi = M<string, int>;

int main(){
    int n;
    cin>>n;
    Vi v1(n/2),v2(n/2);
    V<Pii> p1(100005),p2(100005);
    REP(i,100001){
        p1[i].se = i;
        p2[i].se = i;
    }
    REP(i,n/2){
        cin>>v1[i]>>v2[i];
        p1[v1[i]].fi++;
        p2[v2[i]].fi++;
    }

    sort(ALL(p1),greater<Pii>());
    sort(ALL(p2),greater<Pii>());

    if(p1[0].se != p2[0].se){
        int c1 = n/2 - p1[0].fi;
        int c2 = n/2 - p2[0].fi;
        cout<<c1+c2<<endl;
    }else{
        int c1_1 = n/2 - p1[0].fi;
        int c2_1 = n/2 - p2[1].fi;
        int c1_2 = n/2 - p1[1].fi;
        int c2_2 = n/2 - p2[0].fi;
        cout<<min(c1_1+c2_1,c1_2+c2_2)<<endl;
    }

    return 0;
}