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 V = lines.shift().split(/\s/).map((v) => v - 0);
    let O = V.filter((v, i) => i < N && i % 2 != 0);
    let E = V.filter((v, i) => i < N && i % 2 == 0);
    const same = (v) => v.every((v, i, a) => v == a[0]);
    if (same(O) && same(E) && O[0] != E[0]) {
        console.log(0);
        return;
    }
    let Ev = new Array(1e5 + 1);
    let Ov = new Array(1e5 + 1);
    E.forEach((v) => { Ev[v] = Ev[v] || [v, 0]; Ev[v] = [v, Ev[v][1] + 1]; });
    O.forEach((v) => { Ov[v] = Ov[v] || [v, 0]; Ov[v] = [v, Ov[v][1] + 1]; });
    Ev.sort((a, b) => b[1] - a[1]);
    Ov.sort((a, b) => b[1] - a[1]);
    if (Ov[1] == undefined) Ov[1] = [1, 0];
    if (Ev[1] == undefined) Ev[1] = [1, 0];
    let ans = 0;
    let e0 = E.length - Ev[0][1];
    let e1 = E.length - Ev[1][1];
    let o0 = O.length - Ov[0][1];
    let o1 = O.length - Ov[1][1];
    if (Ev[0][0] != Ov[0][0]) {
        ans = Math.min(...[e0+o0, e0+o1, e1+o0, e1+o1]);
    } else {
        ans = Math.min(...[e0+o1, e1+o0]);
    }

    console.log(ans);
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));