#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 () {
result = 0;
while (true) {
ch = getchar();
if (ch < '0' || ch > '9') break;
result = result*10 + (ch - '0');
}
return result;
}
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;
}
cout << m;
return 0;
}
