集训 D1T1 clique

#include<bits/stdc++.h>
using namespace std;
int n;
struct line{int l,r;}x[200010];
inline bool cmp(line a,line b){return a.l<b.l;}
int main(){
    //freopen("clique.in","r",stdin);
    //freopen("clique.out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        int j,k;
           scanf("%d%d",&j,&k);
          x[i].l=j-k;
          x[i].r=j+k;
    }
    sort(x+1,x+n+1,cmp);
    int k=0;
    for(int i=1;i<=n;i++){
       while(k&&x[i].r<x[k].r)k--;
       x[++k]=x[i];
    }
    n=k;
    for(int i=1,j=-2100000000,k=0;i<=n;i++)
        if(x[i].l>=j){
            j=x[i].r;
             k++;
        }
    printf("%d\n",k);
    return 0;
}