#include"iostream"

 #include"stdio.h"

 #include"algorithm"

 #include"string.h"

 using namespace std;

 const int MAXN=;

 typedef long long ll;

 const ll INF=;

 int used[MAXN];

 struct Cow

 {

     int t,d;

     double div;

 };

 Cow cows[MAXN];

 int n;

 bool Cmp(const Cow a,const Cow b)

 {

     return a.div>b.div;

 }

 ll Solve()

 {

     ll res=;

     ll sum=;

     for(int i=;i<n;i++)

         sum+=cows[i].d;

     for(int i=;i<n;i++){

         sum-=cows[i].d;

         res+=sum**cows[i].t;

     }

     return res;

 }

 int main()

 {

     while(scanf("%d",&n)==)

     {

         for(int i=;i<n;i++){

             scanf("%d%d",&cows[i].t,&cows[i].d);

             cows[i].div=double(cows[i].d)/double(cows[i].t);

         }

         sort(cows,cows+n,Cmp);

         cout<<Solve()<<endl;

     }

     return ;

 }