#include <iostream>
#include <fstream>
using namespace std;

ifstream f("tribute.in");
ofstream g("tribute.out");

int n, dx, dy,ax[50001],ay[50001];

int man(int x, int y, int i, int j)
{	
	int a = 0, b = 0;
	if (i <= x) a = abs(x - i);
	if (j <= y) b = abs(y - j);
	if (i > x)
	{
		x += dx;
		if (i <= x) a = 0;
		else a = abs(x - i);
	}
	if (j > y)
	{
		y += dy;
		if (j <= y) b = 0;
		else b = abs(y - j);
	}
	return a + b;
}


int main()
{
	int i,nr,sum=0;
	double x = 0;
	double y = 0;
	f >> n >> dx >> dy;
	for (i = 1; i <= n; i++)
	{
		f >> ax[i];
		x += ax[i];
		f >> ay[i];
		y += ay[i];
	}
	x = ceil(x/n);
	y = floor(y/n);
	//cout << man(3, 1, 4, 3);
	for (i = 1; i <= n; i++)
		sum += man(x, y, ax[i], ay[i]);
	g << sum;
}