// 2280.Cupboards.cpp : 定义控制台应用程序的入口点。
//

//#include "stdafx.h"
#include<iostream>
using namespace std;


int main()
{
	//int s1[200], s2[200];
	int n,i,x,a0=0,a1=0,b0=0,b1=0,t;
	cin >> n;
	for ( i = 0; i < n; i++)
	{
		//cin >> s1[i];
		//cin >> s2[i];
		cin >> x;
		if (x == 0)
		{
			a0++;
		}
		else
		{
			a1++;
		}
		cin >> x;
		if (x == 0)
		{
			b0++;
		}
		else
		{
			b1++;
		}
	}
	if (a0 <= a1)
	{
		if (b0 <= b1)
		{
			t = a0 + b0;
		}
		else
		{
			t = a0 + b1;
		}
		
	}
	else
	{
		if (b0 <= b1)
		{
			t = a1 + b0;
		}
		else
		{
            t = a1 + b1;
		}
		
	}
	cout << t;

	return 0;
}