#include<bits/stdc++.h>
#define st first
#define nd second
#define pb push_back
#define ppb pop_back
#define ii pair<int,int>
#define ll long long
#define umin(x,y) x=min(x,y)
#define umax(x,y) x=max(x,y)
#define orta ((bas+son)>>1)
#define sz(x) ((int)x.size())
#define all(x) x.begin(),x.end()
#define inf 2000000000
#define N 500005
#define MOD 1000000007
using namespace std;
inline int readInt() {
int x=0; char ch=getchar_unlocked(); bool s=1;
while(ch<'0'||ch>'9'){if(ch=='-')s=0;ch=getchar_unlocked();}
while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+ch-'0';ch=getchar_unlocked();}
return s?x:-x;
}
bitset<10000000> u;
int main() {
int n;
//scanf("%d",&n);
n=readInt();
vector<ii> a(n);
int cnt=n;
for(int i=0;i<n;i++) {
//scanf("%d %d",&a[i].st,&a[i].nd);
a[i].st=readInt();
a[i].nd=readInt();
}
int mn=inf;
for(int i=n-1;i>=0;i--) {
int val=a[i].st-a[i].nd;
if(mn<=val) {
cnt-=!u[i];
u[i]=1;
}
umin(mn,val);
}
int mx=-inf;
for(int i=0;i<n;i++) {
int val=a[i].st+a[i].nd;
if(mx>=val) {
cnt-=!u[i];
u[i]=1;
}
umax(mx,val);
}
printf("%d",cnt);
}
