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)

"use strict";
function Main(input) {
    let lines = input.split("\n");
    let N = lines.shift() - 0;
    let Vc = lines[0].split(/\s/).map((v) => v - 0);
    let a = [{}, {}], sw = 0;
    for (let v of Vc) {
        let b = a[sw][v] || 0;
        a[sw][v] = b + 1;
        sw = (sw + 1) % 2;
    }
    let c = [[], []];
    for (let m = 0; m < 2; m++) {
        for (let v in a[m]) {
            c[m].push({value:v, count:a[m][v]});
        }
    }
    c[0].sort((a, b) => b.count - a.count);
    c[1].sort((a, b) => b.count - a.count);

    let ans = 0;
    let n = N / 2;
    let e0 = c[0][0], e1 = c[0][1] || {value:0, count:0};
    let o0 = c[1][0], o1 = c[1][1] || {value:0, count:0};
    if (e0.value == o0.value) {
        if (e0.count > o0.count) {
            ans += n - e0.count;
            ans += n - o1.count;
        } else if (e0.count < o0.count) {
            ans += n - e1.count;
            ans += n - o0.count;
        } else {
            let ans0 = n - e0.count + n - o1.count;
            let ans1 = n - e1.count + n - o0.count;
            ans = Math.min(ans0, ans1);
        }
    } else {
        ans += n - e0.count;
        ans += n - o0.count;
    }

    console.log(ans);//74371
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));