#include<bits/stdc++.h>
//#include<atcoder/all>
using namespace std;
//using namespace atcoder;
#define rep(i,n) for(ll i=0; i<n; i++)
#define rrep(i,n) for(ll i=n-1; i>=0; i--)
#define print(a) cout<<a<<endl
typedef long long ll;
#define yn(flg) if(flg){cout<<"Yes"<<endl;}else{cout<<"No"<<endl;}
#define YN(flg) if(flg){cout<<"YES"<<endl;}else{cout<<"NO"<<endl;}
#define so(a) sort(a.begin(),a.end())
#define mp make_pair
#define vi vector<int>
#define vl vector<ll>
#define vs vector<string>
#define pb push_back
#define a2i(a,s) (ll)(a-s)
#define i2a(s,a) (char)(s+a)
#define ssize(a) a.size()
typedef pair<int, int> Pii;
typedef pair<int, ll> Pil;
typedef pair<pair<ll,ll>,ll> P3;
typedef pair<pair<ll,ll>,pair<ll,ll>> P4;
typedef pair<ll, ll> Pll;
typedef pair<ll,Pll> Plll;
typedef pair<Pii, int> Piii;
const ll INF = 1000000000000000000;
template<class T> inline bool chmin(T& a, T b) {
if (a > b) {
a = b;
return true;
}
return false;
}
template<class T> inline bool chmax(T& a, T b) {
if (a < b) {
a = b;
return true;
}
return false;
}
using ull=unsigned long long;
//ある区間の最大値を求めたいとき
class SegmentTree{
public:
vector<ll> dat;
ll siz=1;
//初期化
void init(ll n){
siz=1;
while(siz<n)siz*=2;
for(ll i=0;i<=siz*2;i++)dat.push_back(0);
}
//配列A[pos]をｘに変更
void update(ll pos,ll x){
pos=pos+siz-1;
dat[pos]=x;
while(pos>=2){
pos/=2;
dat[pos]=max(dat[pos*2],dat[pos*2+1]);
}
}
//A[l]-A[r-1]の最大値
ll query(ll l,ll r,ll a,ll b,ll u){
//uは現在のセグ木の番号a,bはそれに対する範囲
if(r<=a||b<=l)return 0;
if(l<=a&&b<=r)return dat[u];
ll m=(a+b)/2;
ll ansl=query(l,r,a,m,u*2);
ll ansr=query(l,r,m,b,u*2+1);
return max(ansl,ansr);
}
};
class SegmentTree se;
int main(){
//入力
cin.tie(0);
ios::sync_with_stdio(0);
ll n;
cin>>n;
vector<ll> l(n+1);
vector<ll> r(n+1);
priority_queue<Pll,vector<Pll>,greater<Pll> > que;
se.init(n);
vector<ll> v(n+1,0);
rep(i,n){
cin>>l[i+1]>>r[i+1];
if(i-l[i+1]>0)que.push({i-l[i+1],i+1});
}
//判定
vector<ll> dp(n+1);
for(ll i=1;i<=n;i++){
ll V=0;
for(ll j=i-1;j>=0;j--){
if(j>=i-l[i])continue;
if(j+r[j]<i)V=max(V,dp[j]);
}
dp[i]=V+1;
// dp[i]=v[i]+1;
// if(i+r[i]+1<=n)se.update(i+r[i]+1,dp[i]);
//
// while(!que.empty()){
// ll pos=que.top().second,cost=que.top().first;
// if(cost!=i)break;
// que.pop();
// v[pos]=se.query(1,pos+1,1,se.siz+1,1);
// }
// cout<<dp[i]<<" "<<i<<endl;
}
ll ans=0;
for(ll i=1;i<=n;i++)ans=max(ans,dp[i]);
cout<<ans<<endl;
return 0;
}
