#include <bits/stdc++.h>
using namespace std;
typedef pair<int, int> pii;
int N;
long long ans;
pii A[202020];
struct Node{
vector<pii> V;
Node *lc=NULL, *rc=NULL;
};
void update(Node *now, int s, int e, pii P){
if (e < P.second || P.second < s) return;
if (s == e) {
now->V.push_back(P);
return;
}
int mid = (s+e)/2;
if (now->lc == NULL) now->lc = new Node;
update(now->lc, s, mid, P);
if (now->rc == NULL) now->rc = new Node;
update(now->rc, mid+1, e, P);
while (!now->V.empty() && now->V.back().second < P.second) now->V.pop_back();
now->V.push_back(P);
}
int query(Node *now, int s, int e, int xlim, int ylim){
if (ylim < s) return xlim;
if (e <= ylim){
auto k = lower_bound(now->V.begin(), now->V.end(), pii(xlim, 0));
if (k == now->V.end()) return xlim;
ans += now->V.end() - k;
return now->V.back().first;
}
int mid = (s+e)/2;
if (now->rc != NULL) xlim = query(now->rc, mid+1, e, xlim, ylim);
if (now->lc != NULL) xlim = query(now->lc, s, mid, xlim, ylim);
return xlim;
}
int main(){
scanf("%d", &N);
for (int i=1; i<=N; i++) scanf("%d %d", &A[i].first, &A[i].second);
sort(A+1, A+N+1, [&](pii X, pii Y){
return X.second < Y.second;
});
for (int i=1; i<=N; i++) A[i].second = i;
sort(A+1, A+N+1);
Node *Tree = new Node;
for (int i=1; i<=N; i++){
query(Tree, 1, N, 0, A[i].second);
update(Tree, 1, N, A[i]);
}
printf("%lld\n", ans);
return 0;
}
