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 Pascal (FPC 2.6.2) (judge verdict: Accepted)

var n:longint;
x,i,m1,m11,m22,m2:longint;
a,b:array[0..100001]of integer;
begin 
	read(n);
	a[0]:=0;b[0]:=0;//a ou
	m1:=0;m2:=0;
	for i:=1 to n do 
	begin 
		read(x);
		if i mod 2=0 then 
		begin 
			inc(a[x]);
			if (a[x]>a[m1]) and (x<>m1) then begin m11:=m1;m1:=x;end
			else if (a[x]>a[m11]) and (x<>m11) and (x<>m1) then m11:=x;
		end
		else begin 
			inc(b[x]);
			if (b[x]>b[m2]) and (x<>m2) then begin m22:=m2;m2:=x;end
			else if (b[x]>b[m22]) and (x<>m22) and (x<>m2) then m22:=x;
		end;
	end;
	if m1=m2 then 
	begin 
		if a[m11]+b[m2]>a[m1]+b[m22] then write(n-a[m11]-b[m2])
			else write(n-a[m1]-b[m22]);
		exit;
	end;       
	write(n-a[m1]-b[m2]);
end.