C++ :

#include<bits/stdc++.h>
using namespace std;
int n,max1,x,y,ans;
struct dian{
	int x,y,qian,hou,bj;
}a[1001];
int cmp( dian a,dian b)
{
	return a.hou<b.hou;
}
int main()
{
	cin>>n;
	for(int i=0;i<n;i++)
	{
		cin>>x>>y;a[i].bj=0;
//		if(a[i].x>max1) max1=a[i].x;
		a[i].qian=x-y;a[i].hou=x+y;
		if(a[i].qian<1) a[i].qian=1;
//		if(a[i].hou>max1) a[i].hou=max1;	
	}
	sort(a,a+n,cmp);
//	for(int i=0;i<n;i++)
//		cout<<i<<" "<<a[i].qian<<" "<<a[i].hou<<" "<<a[i].bj<<endl;
	for(int i=0;i<n;i++)
	{
		if(a[i].bj==0){
			ans++;
			for(int j=i+1;j<n;j++)
				if(a[j].qian<=a[i].hou ) a[j].bj=1;
				else break;
		}
		
	}
	cout<<ans<<endl;
	return 0;
}