#include<bits/stdc++.h>
using namespace std;
#define lli long long int
#define mt make_tuple
#define mp make_pair
int main(){
lli x,i,a,b,mx=0,m,n;
cin>>x;
priority_queue<pair<lli,lli>>pq;
vector<tuple<lli,lli,lli>>q(x);//(from the one who comes, the one who goes, itself)
vector<lli>v(x+2,0),l={0,999999999};
for(lli i=1;i<=x;i++){
cin>>a>>b;
a++;
b++;
if(a>i)a=i;
if(b+i>x)b=x-i+1;
a=i-a;
b=i+b;
q[i-1]=mt(a,b,i);
}
sort(q.begin(),q.end());
for(auto t:q){
a=get<0>(t);
b=get<1>(t);
i=get<2>(t);
while(!pq.empty()&&999999999-pq.top().first<=a){
n=v[999999999-pq.top().first];
m=pq.top().second;
if(n+1==l.size()){
l[n]=m;
l.push_back(999999999);
}
else l[n]=min(l[n],m);
pq.pop();
}
m=upper_bound(l.begin(),l.end(),i)-l.begin()-1;
v[i]=m+1;
pq.push(mp(999999999-i,b));
mx=max(mx,v[i]);
}
cout<<mx<<endl;
}
