527D - Clique Problem - CodeForces Solution

#include<bits/stdc++.h>
using namespace std;
int n,ans;
struct node{
int l,r;
}a[200005];
bool cmp(node x,node y){
if(x.r!=y.r)return x.r<y.r;
return x.l<y.l;
}
int main(){
cin>>n;
for(int i=1;i<=n;i++){
int x,y;
cin>>x>>y;
a[i].l=x-y;a[i].r=x+y;
}
sort(a+1,a+n+1,cmp);
int r=-(1<<30);
for(int i=1;i<=n;i++){
if(a[i].l>=r){
ans++;
r=a[i].r;
}
}
cout<<ans;
return 0;
}