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: Time Limit Exceeded)

"use strict";
    
const main = arg => {
    arg = arg.trim().split("\n");
    
    const N    = ~~arg[0].split(" ")[0];
    const a    = arg[1].split(" ");
    
    const set = new Set(a);
    
    if(set.size === 1) {
        console.log(N / 2);
        return;
    }
    
    const oddMap  = [];
    const evenMap = [];
    let oddSet = new Set();
    let evenSet = new Set();
    
    for(let i in a) {
        if(i % 2 === 0) {
            
            if(oddSet.has(a[i])) {
                let exist = oddMap.filter(n=>n.val===a[i]);
                exist.map(n=>n.cnt++);
            } else {
                oddSet.add(a[i]);
                oddMap.push({val:a[i], cnt: 1});
            }
        } else {
            
            if(evenSet.has(a[i])) {
                let exist = evenMap.filter(n=>n.val===a[i]);
                exist.map(n=>n.cnt++);
            } else {
                evenSet.add(a[i]);
                evenMap.push({val:a[i], cnt: 1});
            }
        }
    }
    
    const oddMin1  = oddMap.sort((a,b)=>b.cnt - a.cnt)[0].cnt;
    let   oddMin2;
    
    if(oddSet.size >= 2) {
        oddMin2  = oddMap.sort((a,b)=>b.cnt - a.cnt)[1].cnt;
    }
    
    const evenMin1 = evenMap.sort((a,b)=>b.cnt - a.cnt)[0].cnt;
    let   evenMin2;
    
    if(evenSet.size >= 2) {
        evenMin2 = evenMap.sort((a,b)=>b.cnt - a.cnt)[1].cnt;
    }
    
    let answer;
    
    if(oddSet.size === 1 && evenSet.size === 1) {
        answer = 0;
    } else {
        answer = N - oddMin1 - evenMin1;
        
        if(oddMin1 === evenMin1) {
            answer = Math.min((N - oddMin1 - evenMin2), (N - oddMin2 - evenMin1));
        }
    }
    
    console.log(answer);
}
main(require('fs').readFileSync('/dev/stdin', 'utf8'));