#include <cstdio> #include <cstring> #include <algorithm> #include <set> using namespace std; typedef pair<int,int> pi; struct pt{int x,y;}pos[200005]; int cmp1(pt a, pt b){return a.x<b.x;} int cmp2(pt a, pt b){return a.y<b.y;} int a[200005],n; int lim, tree[270000]; void initTree(int n){ for(lim = 1; lim <= n; lim <<= 1); memset(tree,0,sizeof(tree)); } void add(int x){ while (x <= lim) { tree[x]++; x += x & -x; } } int sum(int x){ int res = 0; while (x) { res += tree[x]; x -= x & -x; } return res; } long long f(int s, int e){ if(s == e) return 0; int m = (s+e)/2; long long res = f(s,m) + f(m+1,e); initTree(n+1); set<pi> s_left, s_right, s_right_old; set<pi>::iterator it; for (int i=m; i>=s; i--) { it = s_left.upper_bound(pi(a[i],0)); int lim; if(it == s_left.end()) lim = n+1; else lim = (*it).first - 1; s_left.insert(pi(a[i],lim)); } for (int i=m+1; i<=e; i++) { it = s_right_old.upper_bound(pi(a[i],0)); int lim; if(it == s_right_old.begin()) lim = -1; else{ it--; lim = (*it).first; } s_right_old.insert(pi(a[i],lim)); } for (it = s_right_old.begin(); it != s_right_old.end(); it++) { pi x = *it; swap(x.first,x.second); s_right.insert(x); } s_left.insert(pi(1e9,1e9)); s_right.insert(pi(1e9,1e9)); for (int i=s; i<=e; i++) { if((*s_left.begin()).first < (*s_right.begin()).first){ it = s_left.begin(); res += sum((*it).second) - sum((*it).first - 1); s_left.erase(it); } else{ it = s_right.begin(); add((*it).second); s_right.erase(it); } } return res; } int main(){ scanf("%d",&n); for (int i=0; i<n; i++) { scanf("%d %d",&pos[i].x,&pos[i].y); } sort(pos,pos+n,cmp2); for (int i=0; i<n; i++) { pos[i].y = i+1; } sort(pos,pos+n,cmp1); for (int i=0; i<n; i++) { a[i] = pos[i].y; } long long r = f(0,n-1); printf("%lld",r); }