#include <stdio.h>#include <string.h>#include <algorithm>#define MAX(a,b) (a>b?a:b)#define ABS(a) ((a)>0?(a):-1*(a))#define TK(a) (a&(a^(a-1)))#define N 20005using namespace std;struct Node{ long long v,x; bool operator<(const Node & a)const { return v<a.v; }}node[N];long long num[2][N];long long rsum(int pos,int d){ long long ans=0; while(pos>0) { ans+=num[d][pos]; pos-=TK(pos); } return ans;}void toput(int pos,long long v,int d){ while(pos<=20000) { num[d][pos]+=v; pos+=TK(pos); }}int main(){ int n; scanf("%d",&n); memset(num,0,sizeof(num)); for(int i=1;i<=n;i++) scanf("%lld%lld",&node[i].v,&node[i].x); sort(node+1,node+1+n); long long ans=0; for(int i=1;i<=n;i++) { long long a=rsum(node[i].x,0),b=rsum(node[i].x,1); ans+=(node[i].x*a-b+rsum(20000,1)-b-(i-1-a)*node[i].x)*node[i].v; toput(node[i].x,1,0); toput(node[i].x,node[i].x,1); } printf("%lldn",ans);}
