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# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
class Program
{
  static void Main(string[] args)
  {
    var n=Read();
    var v=Read(n);
    long[] a=new long[100000];
    long[] b=new long[100000];
    for(long i=0;i<n;i+=2){
      a[v[i]-1]++; b[v[i+1]-1]++;
    }
    long a1=0,a2=0,b1=0,b2=0,an1=0,bn1=0;
    for(long i=0;i<100000;i++){
      if(a[i]>a1){
        a2=a1; a1=a[i]; an1=i;
      }
      if(b[i]>b1){
        b2=b1; b1=b[i]; bn1=i;
      }
    }
    if(an1!=bn1){Write(n-a1-b1);}
    else{
      if(a1+b2>a2+b1){
        Write(n-a1-b2);
      }else{
        Write(n-a2-b1);
      }
    }
  }

  static void Write(string s) { Console.WriteLine(s); return; }
  static void Write(long n) { Console.WriteLine(n.ToString()); return; }
  static string ReadStr() { return Console.ReadLine(); }
  static string[] ReadStrs() { return Console.ReadLine().Split(' '); }
  static long Read() { return long.Parse(Console.ReadLine()); }
  static long[] Read(long n) {
    long[] p = new long[n];
    string[] t = Console.ReadLine().Split(' ');
    for(long i = 0; i < n; i++) { p[i] = long.Parse(t[i]); }
    return p;
  }
  static long abs(long n) { return (n > 0) ? n : -n; }
  static long gcd(params long[] n) { long p = n[0]; for (long i = 1; i < n.Length; i++) { p = gcd(p, n[i]); } return p; }
  static long gcd(long a, long b) { return (a==0)?b:gcd(b % a, a); }
  static long lcm(params long[] n) { long p = n[0]; for (long i = 1; i < n.Length; i++) { p = lcm(p, n[i]); } return p; }
  static long lcm(long a, long b) { return a * b / gcd(a, b); }
  static long max(params long[] n) { long p = n[0]; for (long i = 1; i < n.Length; i++) { p = (p>n[i])?p:n[i]; } return p; }
  static long min(params long[] n) { long p = n[0]; for (long i = 1; i < n.Length; i++) { p = (p<n[i])?p:n[i]; } return p; }
  static void YN(bool t) { Console.WriteLine(t ? "YES" : "NO"); }
  static void Yn(bool t) { Console.WriteLine(t ? "Yes" : "No"); }
  static void yn(bool t) { Console.WriteLine(t ? "yes" : "no"); }
  static string clip(string s, int start, int count) {
    if (start + count < s.Length) { s = s.Remove(start + count); }
    if (start > 0) { s = s.Remove(0, start); }
    return s;
  }
}