#include <bits/stdc++.h>
#define ll long long
#define ldb long double
#define endl '\n'
#define For(i,l,r) for(int i=l;i<=r;i++)
#define ForD(i,r,l) for(int i=r;i>=l;i--)
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
#define sz(x) (signed)x.size()
#define unq(x) x.resize(unique(all(x))-x.begin())
#define F "TASK"
#define fio freopen(F".INP","r",stdin);freopen(F".OUT","w",stdout);
#ifdef NCGM
#include"debug.h"
#else
#define debug(...) "fr";
#endif
using namespace std;
const int N=5e5+3;
int n,p[N];
pair<int,int> a[N];
set<pair<int,int>> an,cut;
struct SegTree {
bool rizz=0;
pair<int,int> tr[N*4];
pair<int,int> merge(const pair<int,int> a, const pair<int,int> b) {
if (rizz==0 || a.ff!=b.ff) return max(a,b);
return min(a,b);
}
void build(int id,int l,int r,pair<int,int> *src) {
if (l==r) return void(tr[id]={(rizz==0)?src[l].ss-src[l].ff:src[l].ss+src[l].ff,l});
int mid=l+r>>1;
build(id*2,l,mid,src);
build(id*2+1,mid+1,r,src);
tr[id]=merge(tr[id*2],tr[id*2+1]);
}
void update(int id,int l,int r,int u) {
if (l>u || r<u) return;
int mid=l+r>>1;
if (l==r) return void(tr[id]={(int)(-2e9),0});
update(id*2,l,mid,u);
update(id*2+1,mid+1,r,u);
tr[id]=merge(tr[id*2],tr[id*2+1]);
}
pair<int,int> query(int id,int l,int r,int u,int v) {
if (l>v || r<u) return {(int)(-2e9),0};
if (l>=u && r<=v) return tr[id];
int mid=l+r>>1;
return merge(query(id*2,l,mid,u,v),query(id*2+1,mid+1,r,u,v));
}
} st,st1;
int solve(int l,int r) {
if (l>r) return 0;
int ans=2;
pair<int,int> sus=st.query(1,1,n,l,r),sus1=st1.query(1,1,n,l,r);
swap(sus.ff,sus.ss);
swap(sus1.ff,sus1.ss);
if (sus.ss<=-2e9) return 0;
if (sus.ff+1>sus1.ff-1) {
if (sus.ff==r || st1.query(1,1,n,sus.ff+1,r).ff<=a[sus.ff].ff+a[sus.ff].ss) return 1;
if (sus1.ff==l || st.query(1,1,n,l,sus1.ff-1).ff<=a[sus1.ff].ss-a[sus1.ff].ff) return 1;
return 2;
}
For(i,l,sus.ff) {
if (an.find({a[i].ss-a[i].ff,i})!=an.end()) an.erase({a[i].ss-a[i].ff,i});
if (cut.find({a[i].ss+a[i].ff,i})!=cut.end()) cut.erase({a[i].ss+a[i].ff,i});
}
For(i,sus1.ff,r) {
if (an.find({a[i].ss-a[i].ff,i})!=an.end()) an.erase({a[i].ss-a[i].ff,i});
if (cut.find({a[i].ss+a[i].ff,i})!=cut.end()) cut.erase({a[i].ss+a[i].ff,i});
}
if (sz(an)) {
auto it=an.upper_bound({a[sus1.ff].ss-a[sus1.ff].ff,N+69});
if (it!=an.begin()) {
it=prev(it);
while(it!=an.begin()) {
int tmp=it->ss;
it=prev(it);
an.erase(next(it));
cut.erase({a[tmp].ff+a[tmp].ss,tmp});
st.update(1,1,n,tmp);
st1.update(1,1,n,tmp);
}
int tmp=it->ss;
an.erase(it);
cut.erase({a[tmp].ff+a[tmp].ss,tmp});
st.update(1,1,n,tmp);
st1.update(1,1,n,tmp);
}
}
if (sz(cut)) {
auto it=cut.upper_bound({a[sus.ff].ss+a[sus.ff].ff,N+69});
if (it!=cut.begin()) {
it=prev(it);
while(it!=cut.begin()) {
int tmp=it->ss;
it=prev(it);
cut.erase(next(it));
an.erase({a[tmp].ss-a[tmp].ff,tmp});
st.update(1,1,n,tmp);
st1.update(1,1,n,tmp);
}
int tmp=it->ss;
cut.erase(it);
an.erase({a[tmp].ss-a[tmp].ff,tmp});
st.update(1,1,n,tmp);
st1.update(1,1,n,tmp);
}
}
ans+=solve(sus.ff+1,sus1.ff-1);
return ans;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n;
For(i,1,n) cin >> a[i].ff >> a[i].ss;
sort(a+1,a+1+n);
st1.rizz=1;
st.build(1,1,n,a);
st1.build(1,1,n,a);
For(i,1,n) {
an.insert({a[i].ss-a[i].ff,i});
cut.insert({a[i].ss+a[i].ff,i});
}
cout << solve(1,n) << endl;
return 0;
}
