#include <bits/stdc++.h>
using namespace std;
typedef pair<long long, long long> pi;
long long ls(long long x){ return (x)&(-x); }
long long n, t, fwmul[10005], fwf[10005], fws[10005], fwc[10005];
pi a[100000];
void pu(long long *tree, long long x, long long y){
for(; x <= 10001; x += ls(x)) tree[x] += y;
}
long long pq(long long *tree, long long x){
long long t = 0;
for(; x; x -= ls(x)) t += tree[x];
return t;
}
long long rq(long long *tree, long long s, long long e){
return pq(tree, e)-pq(tree, s-1);
}
int main(){
cin >> n;
for(int i = 0; i < n; i++) cin >> a[i].first >> a[i].second;
sort(a, a+n);
for(int i = 0; i < n; i++){
//cur: b, d
//prev: a, c
//d > c: bd+ac-bc-ad
t += a[i].first*a[i].second*rq(fwc, 1, a[i].second-1)+rq(fwmul, 1, a[i].second-1); //bd+ac
t -= a[i].first*rq(fws, 1, a[i].second-1)+rq(fwf, 1, a[i].second-1)*a[i].second; //-bc-ad
//c > d: bc+ad-ac-bd
t += a[i].first*rq(fws, a[i].second+1, 10001)+rq(fwf, a[i].second+1, 10001)*a[i].second; //bc+ad
t -= a[i].first*a[i].second*rq(fwc, a[i].second+1, 10001)+rq(fwmul, a[i].second+1, 10001); //-bd-ac
//update
pu(fwmul, a[i].second, a[i].first*a[i].second);
pu(fwf, a[i].second, a[i].first);
pu(fws, a[i].second, a[i].second);
pu(fwc, a[i].second, 1);
}
cout << t;
}
