#include <cstdio>

#include <cstring>

#include <iostream>

#include <algorithm>

using namespace std;

#define maxn 20005

struct CowType {

    int vi,xi;

};

struct CowType cow[maxn];

struct TreeNodeType {

    int l,r,xx,sum,mid;

};

struct TreeNodeType tree[maxn<<];

int n;

long long ans,sx,ss;

inline void in(int &now)

{

    char Cget=getchar();now=;

    while(Cget>''||Cget<'') Cget=getchar();

    while(Cget>=''&&Cget<='')

    {

        now=now*+Cget-'';

        Cget=getchar();

    }

}

bool cmp(CowType aa,CowType bb)

{

    return aa.vi<bb.vi;

}

void tree_build(int now,int l,int r)

{

    tree[now].l=l,tree[now].r=r;

    if(l==r) return ;

    tree[now].mid=l+r>>;

    tree_build(now<<,l,tree[now].mid);

    tree_build(now<<|,tree[now].mid+,r);

}

void tree_add(int now,int to)

{

    if(tree[now].l==tree[now].r)

    {

        tree[now].sum++;

        tree[now].xx+=cow[to].xi;

        return ;

    }

    if(cow[to].xi<=tree[now].mid) tree_add(now<<,to);

    else tree_add(now<<|,to);

    tree[now].xx=tree[now<<].xx+tree[now<<|].xx;

    tree[now].sum=tree[now<<].sum+tree[now<<|].sum;

}

void tree_query(int now,int l,int r)

{

    if(tree[now].l==l&&tree[now].r==r)

    {

        sx+=tree[now].xx,ss+=tree[now].sum;

        return ;

    }

    if(l>tree[now].mid) tree_query(now<<|,l,r);

    else if(r<=tree[now].mid) tree_query(now<<,l,r);

    else

    {

        tree_query(now<<,l,tree[now].mid);

        tree_query(now<<|,tree[now].mid+,r);

    }

}

int main()

{

    in(n);

    for(int i=;i<=n;i++) in(cow[i].vi),in(cow[i].xi);

    sort(cow+,cow+n+,cmp),tree_build(,,),tree_add(,);

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

    {

        tree_add(,i);

        sx=,ss=,tree_query(,,cow[i].xi-);

        ans+=(ss*cow[i].xi-sx)*cow[i].vi;

        sx=,ss=,tree_query(,cow[i].xi+,);

        ans+=(sx-ss*cow[i].xi)*cow[i].vi;

    }

    cout<<ans;

    return ;

}