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: Wrong Answer)

function main(input) {
  var N = input[0].split(" ")[0]-0;
  var list = input[1].split(" ").map(v=>v-0);
  var a = {};
  var b = {};
  list.forEach((v,i)=>{
    if(i%2==0){
      a[v] = (a[v]||0)+1;
    }else{
      b[v] = (b[v]||0)+1;
    }
  });
  var alist = Object.keys(a).sort((aa,bb)=>a[bb]-a[aa]);
  var blist = Object.keys(b).sort((aa,bb)=>b[bb]-b[aa]);
  var ans = 0;
  if(alist[0]!=blist[0]){
    alist.filter((v,i)=>i>0).forEach(v=>ans+=a[v]);
    blist.filter((v,i)=>i>0).forEach(v=>ans+=b[v]);
  }else{
    if(a[alist[0]]>b[blist[0]]){
      alist.filter((v,i)=>i>0).forEach(v=>ans+=a[v]);
      blist.filter((v,i)=>i>1||i==0).forEach(v=>ans+=b[v]);
    }else if(a[alist[0]]>b[blist[0]]){
      blist.filter((v,i)=>i>0).forEach(v=>ans+=b[v]);
      alist.filter((v,i)=>i>1||i==0).forEach(v=>ans+=a[v]);
    }else if(a[alist[1]]>b[blist[1]]){
      alist.filter((v,i)=>i>0).forEach(v=>ans+=a[v]);
      blist.filter((v,i)=>i>1||i==0).forEach(v=>ans+=b[v]);
    }else{
      blist.filter((v,i)=>i>0).forEach(v=>ans+=b[v]);
      alist.filter((v,i)=>i>1||i==0).forEach(v=>ans+=a[v]);
    }
      
      
  }
  console.log(ans);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"))