#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(){ for(lim = 1; lim <= n+1; 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){ long long res = 0; if(e - s < 200){ for (int i=s; i<=e; i++) { int lower=a[i]; int upper=1987654321; for (int j=i+1; j<=e; j++) { if(upper>a[j] && a[j]>lower){ upper=a[j]; res++; } } } return res; } int m = (s+e)/2; res = f(s,m) + f(m+1,e); initTree(); set<pi> s_left, s_right, s_right_old; set<pi> ::iterator it,it2; int lim; for (int i=m; i>=s; i--) { it = s_left.upper_bound(pi(a[i],0)); 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)); if(it == s_right_old.begin()) lim = -1; else{ it--; lim = (*it).first; } s_right_old.insert(pi(a[i],lim)); s_right.insert(pi(lim,a[i])); } s_left.insert(pi(1e6,1e6)); s_right.insert(pi(1e6,1e6)); it = s_left.begin(); it2 = s_right.begin(); for (int i=s; i<=e; i++) { if((*it).first < (*it2).first){ res += sum((*it).second) - sum((*it).first - 1); it++; } else{ add((*it2).second); it2++; } } 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); }