#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
#define ll long long
#define ld long double
#define pll pair<ll,ll>
#define pb push_back
ll T=1,n,nq,x,y,ind,t,l[200009],r[20009],dp[10009],k,mx,rs=0,c,pr,lft,a[2000009];
//map<ll,ll>ma;
void slv()
{
cin>>n;
for(int i=1;i<=n;i++)
{
cin>>l[i]>>r[i];
l[i]=max(0ll,i-l[i]);
r[i]=min(n+1,i+r[i]);
}
for(int i=1;i<=n;i++)
{
dp[i]=1;
}
for(int s=1;s<=n;s++)
{
for(int j=r[s]+1;j<=n;j++)
{
if(l[j]>s)dp[j]=max(dp[j],dp[s]+1);
}
rs=max(rs,dp[s]);
}
cout<<rs<<endl;
}
int main() {
//freopen("feast.in", "r", stdin);
//freopen("feast.out", "w", stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//cin>>T;
while(T--)
slv();
return 0;
}
