#include<stdio.h>struct point{    int x,y;};struct point p[10020];void sort(int a,int b){    int i,j;    for(i=a+1;i<b;i++){        struct point temp=p[i];        j=i-1;        while(temp.y<p[j].y&&j>=0) p[j+1]=p[j--];        if(j!=i-1)            p[j+1]=temp;    }}int main(){    int n;    scanf("%d",&n);    int i;    for(i=0;i<n;i++)        scanf("%d%d",&p[i].x,&p[i].y);    sort(0,n);    int sum=0;    int head=0,tail=n-1;    while(head<tail) sum+=(p[tail--].y-p[head++].y);    printf("%d\n",sum);    return 0;}