#include<bits/stdc++.h>
using namespace std ;
#define maxn 500009
#define ll long long
#define fi first
#define se second
#define pb push_back
#define left id<<1
#define right id<<1|1
#define re exit(0);
#define _lower(x) lower_bound(v.begin(),v.end(),x)-v.begin()+1
const int mod = 1e9+7 ;
const int INF = 1e9 ;
const int LOG = 18 ;
typedef vector<int> vi ;
typedef pair<int,int> pii ;
typedef vector<pii> vii ;
typedef vector<ll> vl ;
typedef pair<ll,ll> pll ;
typedef vector<pll> vll ;
void add ( int&a , int b ) { if ((a+=b) > mod ) a -= mod ; }
void sub ( int&a , int b ) { if ((a-=b) < 0 ) a += mod ; }
template<typename T> void chkmin(T& x, T y) {if(x > y) x = y;}
template<typename T> void chkmax(T& x, T y) {if(x < y) x = y;}
void rf ( )
{
freopen ("bai1.inp","r",stdin) ;
// freopen ("bai1.out","w",stdout) ;
}
int _pow ( int a , int n )
{
if ( n == 0 ) return 1 ;
int res = _pow ( a , n / 2 ) ;
if ( n % 2 ) return ( 1ll * res * res % mod * a % mod ) ;
else return ( 1ll * res * res % mod ) ;
}
int n ;
struct shape {
int x , h , fac_x ;
} a [maxn] ;
void mapping ()
{
vi v ;
for ( int i = 1 ; i <= n ; i ++ ) v . pb (a[i].x) ;
sort(v.begin(),v.end()) ;
v.resize(unique(v.begin(),v.end())-v.begin()) ;
for ( int i = 1 ; i <= n ; i ++ ) a [i].fac_x = _lower(a[i].x) ;
}
int bit1 [maxn] , bit2 [maxn] ;
void update_bit1 ( int x , int y )
{
while ( x ) chkmax (bit1[x],y) , x -= (x&-x) ;
}
int get_bit1 ( int x )
{
int res = -2e9 ;
while ( x < maxn ) chkmax (res,bit1[x]) , x += (x&-x) ;
return res ;
}
void update_bit2 ( int x , int y )
{
while ( x < maxn ) chkmax (bit2[x],y) , x += (x&-x) ;
}
int get_bit2 ( int x )
{
int res = -2e9 ;
while ( x ) chkmax (res,bit2[x]) , x -= (x&-x) ;
return res ;
}
bool cmp_h ( shape u , shape v )
{
return u.h > v.h ;
}
int main ( )
{
ios_base :: sync_with_stdio (0) ;
cin.tie(0) ; cout.tie(0) ;
// rf () ;
cin >> n ;
for ( int i = 1 ; i <= n ; i ++ ) cin >> a[i].x >> a [i].h ;
mapping () ;
sort (a+1,a+n+1,cmp_h) ;
int res = 0 ;
memset ( bit1 , -0x3f , sizeof bit1 ) ;
memset ( bit2 , -0x3f , sizeof bit2 ) ;
for ( int i = 1 ; i <= n ; i ++ )
{
int x = a[i].x , h = a[i].h , fac_x = a[i].fac_x ;
bool ok = false ;
if ( get_bit1 (fac_x) >= h - x ) ok |= true ;
if ( get_bit2 (fac_x) >= h + x ) ok |= true ;
res += (!ok) ;
update_bit1 (fac_x,h-x) ;
update_bit2 (fac_x,h+x) ;
}
cout << res ;
}
//-std=c++11
// check special
// range , time , error , stay hard stay hard
// there is no tomorrow
