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 JavaScript (node.js v5.12) (judge verdict: Accepted)

function gets(str){
  this._s = str.split("\n");
  this._y = 0;
};
gets.prototype = {
  a: function(f){
    var s = this._s, y = this._y, r;
    if(typeof s[y] === "string")s[y] = s[y].split(" ").reverse();
    r = s[y].pop();
    if(!s[y].length)this._y++;
    return f?r:+r;
  },
  l: function(f){
    var s = this._s[this._y++].split(" ");
    return f?s:s.map(a=>+a);
  },
  m: function(n,f){
    var s = this._s, y = this._y, r = [], i = 0;
    if(f)for(;i < n; i++)r[i] = s[y+i].split(" ");
    else for(;i < n; i++)r[i] = s[y+i].split(" ").map(a=>+a);
    this._y += n;
    return r;
  },
};
var o=new gets(require("fs").readFileSync("/dev/stdin","utf8"));

console.log(main());
function main(){
  var n = o.a();
  var v = o.l();
  var a = {}, b = {};
  for(var i = 0; i < n; i++){
    if(a[v[i]])a[v[i]]++;
    else a[v[i]] = 1;
    i++;
    if(b[v[i]])b[v[i]]++;
    else b[v[i]] = 1;
  }
  var c = [], d = [];
  for(i in a){
    c.push([i,a[i]]);
  }
  for(i in b){
    d.push([i,b[i]]);
  }
  c.sort((a,b)=>b[1]-a[1]);
  d.sort((a,b)=>b[1]-a[1]);
  if(c[0][0] !== d[0][0])return n-c[0][1]-d[0][1];
  if(c.length !== 1){
    if(d.length !== 1){
      return n-Math.max(c[1][1]+d[0][1],c[0][1]+d[1][1]);
    }else return n-c[1][1]-d[0][1];
  }
  if(d.length !== 1)return n-c[0][1]-d[1][1];
  return n / 2;
}