#include <cstdio>

#include <algorithm>

using namespace std;

const int N=;

int n;

struct point{int x,w;}a[N];

inline bool cmp(point a,point b){return a.x<b.x;}

struct node{int l,r;}line[N];

inline bool cmp1(node a,node b){return (a.r!=b.r)?(a.r<b.r):(a.l<b.l);}

int main()

{

    int i,re=,tmp=-2e9; scanf("%d",&n); for(i=;i<=n;i++)scanf("%d%d",&a[i].x,&a[i].w); sort(a+,a+n+,cmp);

    for(i=;i<=n;i++)line[i].l=a[i].x-a[i].w,line[i].r=a[i].x+a[i].w; sort(line+,line+n+,cmp1);

    for(i=;i<=n;i++)

    {

        if(tmp<=line[i].l){tmp=line[i].r; re++;}

    }printf("%d\n",re);

}