#include<bits/stdc++.h> using namespace std; const int MXN = 500005; int N, ns[MXN], nn, mxv[MXN << 2]; struct Board{ int l, r; }bds[MXN]; inline bool operator<(Board a, Board b){ return a.l == b.l ? a.r > b.r : a.l < b.l; } inline int ls(int p) { return p << 1; } inline int rs(int p) { return p << 1 | 1; } int query(int p, int l, int r, int tl, int tr) { if(l >= tl && r <= tr)return mxv[p]; if(l >= tr || r <= tl)return 0; int mid((l + r) >> 1); return max(query(ls(p), l, mid, tl, tr),query(rs(p), mid, r, tl, tr)); } void change(int p, int l, int r, int t, int v){ if(r - l == 1){ mxv[p] = max(mxv[p], v); return; } int mid((l + r) >> 1); if(t >= mid)change(rs(p), mid, r, t, v); else change(ls(p), l, mid, t, v); mxv[p] = max(mxv[ls(p)], mxv[rs(p)]); } int main() { cin >> N; for(int i(0); i != N; ++i){ cin >> bds[i].l >> bds[i].r; ns[nn++] = bds[i].r; } sort(bds, bds + N); sort(ns, ns + nn); nn = unique(ns, ns + nn) - ns; for(int i(0); i != N; ++i) bds[i].r = lower_bound(ns, ns + nn, bds[i].r) - ns; int ans(0); for(int i(0); i != N; ++i){ int mxp(query(1, 0, nn, bds[i].r, nn)); ans = max(ans, mxp + 1); change(1, 0, nn, bds[i].r, mxp + 1); } cout<<ans; return 0; }