#include <bits/stdc++.h>
#define st first
#define nd second
#define mp make_pair
#define pb push_back
#define coc g[mode][i]
#define sol (k+k)
#define sag (k+k+1)
#define orta ((bas+son)>>1)
#define mod 1000000007
#define inf 1000000009
#define N 10000005
using namespace std;
typedef long long ll;
typedef pair < int , int > ii;
typedef pair < double , double > dd;
int n, m, result;
char ch;
ii a, s[N];
int readInt(){
int res = 0;
char ch = 0;
while(ch < '0') ch = getchar_unlocked();
for(; ch >= '0'; ch = getchar_unlocked()) res = res * 10 + ch - '0';
return res;
}
void writeInt(int v){
char buf[14];
int p = 0;
if(v == 0) buf[p++] = 0;
for(; v; v /= 10) buf[p++] = v % 10;
while(p--) putchar_unlocked(buf[p] + '0');
}
int main(){
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
n = readInt();
for(int i = 1; i <= n; i++){
a.st = readInt();
a.nd = readInt();
while(m and abs(s[m].st - a.st) <= a.nd - s[m].nd)
m--;
if(m and abs(s[m].st - a.st) <= s[m].nd - a.nd)
continue;
s[++m] = a;
}
writeInt(m);
return 0;
}
