#include <iostream> #include <set> #include <vector> #include <algorithm> using namespace std; const int N = (1<<19) + 1; int X[N], E[N], sg1[N<<1], sg2[N<<1]; void insert(int i, int xme, int xpe, int cur = 1, int st = 1, int en = N){ if (i >= en or i < st) return; if (en - st == 1){ sg1[cur] = xme; sg2[cur] = xpe; return; } int lc = cur + cur, rc = lc + 1, mid = (st + en) / 2; insert(i, xme, xpe, lc, st, mid); insert(i, xme, xpe, rc, mid, en); sg1[cur] = max(sg1[lc], sg1[rc]); sg2[cur] = min(sg2[lc], sg2[rc]); } int get1(int i, int v1, int cur = 1, int st = 1, int en = N){ if (en - st == 1) return st; int lc = cur + cur, rc = lc + 1, mid = (st + en) / 2; if (sg1[lc] >= v1) return get1(i, v1, lc, st, mid); if (i >= mid) return get1(i, v1, rc, mid, en); return 0; } int get2(int i, int v2, int cur = 1, int st = 1, int en = N){ if (en - st == 1) return st; int lc = cur + cur, rc = lc + 1, mid = (st + en) / 2; if (sg2[rc] <= v2) return get2(i, v2, rc, mid, en); if (i < mid) return get2(i, v2, lc, st, mid); return 0; } int main(){ ios_base::sync_with_stdio(false); cin.tie(NULL); for (int i=1;i<(N<<1);i++) sg1[i] = -2.1e9, sg2[i] = 2.1e9; int n, Ans = 0, cur; cin>>n; set<pair<int,int>> st0, st1; vector<pair<int,int>> vec(n); for (int i=1, x, e;i<=n;i++){ cin>>x>>e; vec[i-1] = {x, e}; } sort(vec.begin(), vec.end()); for (int i=1;i<=n;i++){ X[i] = vec[i-1].first, E[i] = vec[i-1].second; st1.insert({E[i], i}); insert(i, X[i] - E[i], X[i] + E[i]); } while (st1.size() > 0){ if (st0.size() > 0 and ((*rbegin(st1)).first <= (*rbegin(st0)).first) ) { cur = (*rbegin(st0)).second; st0.erase({E[cur], cur}); } else{ Ans++; cur = (*rbegin(st1)).second; st1.erase({E[cur], cur}); } // cout<<" "<<Ans<<" "<<cur<<endl; while (1){ int g = get1(cur, X[cur] - E[cur]); if (g == 0) break; insert(g, -2.1e9, 2.1e9); // cout<<" - "<<g<<endl; st1.erase({E[g], g}); st0.insert({E[g], g}); } while (1){ int g = get2(cur, X[cur] + E[cur]); if (g == 0) break; // cout<<" + "<<g<<endl; insert(g, -2.1e9, 2.1e9); st1.erase({E[g], g}); st0.insert({E[g], g}); } } cout<<Ans<<'\n'; }