#include <bits/stdc++.h>
#define ii pair<int, int>
#define fi first
#define se second
#define inf 0x3f3f3f3f3f3f3f3f
using namespace std;
using ll = long long;
const ll mod=1e9+7;
const int nx=1e7+5;
int n, ans=0, cur=-1, x, y;
stack<ii> st;
ii p;
bool ok;
static const int BUF_SIZE = 1 << 20;
char buf[BUF_SIZE];
int bi = BUF_SIZE, bn = BUF_SIZE;
inline char readCharFast() {
if (bi >= bn) {
bn = fread(buf, 1, BUF_SIZE, stdin);
bi = 0;
if (bn == 0) return 0;
}
return buf[bi++];
}
inline bool fastReadInt(int &x) {
char c;
do c = readCharFast(); while (c <= ' ' && c != 0);
if (!c) return false;
int sign = 1;
if (c == '-') {
sign = -1;
c = readCharFast();
}
int val = c - '0';
while (1) {
c = readCharFast();
if (c < '0' || c > '9') break;
val = val * 10 + (c - '0');
}
x = val * sign;
return true;
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin>>n;
while(n--)
{
fastReadInt(x);
fastReadInt(y);
ok=1;
while(st.size())
{
p=st.top();
if(x-p.fi<=p.se-y)
{
ok=0;
break;
}
if(x-p.fi<=y-p.se)
st.pop();
else break;
}
if(ok) st.push({x, y});
}
cout<<st.size();
}
