#include <bits/stdc++.h>
using namespace std;
#define pii pair<int, int>
#define mp make_pair
inline int readInt() {
int x = 0;
char ch = getchar();
while (ch < '0' || ch > '9') ch = getchar_unlocked();
while (ch >= '0' && ch <= '9'){
x = (x << 3) + (x << 1) + ch - '0';
ch = getchar_unlocked();
}
return x;
}
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n, x, y;
n = readInt();
stack <pii> st;
while (n--){
x = readInt(), y = readInt();
bool gay = true;
while (!st.empty()){
if (abs(x-st.top().first)<=st.top().second-y){
gay = false;
break;
}
if (abs(x-st.top().first)<=y-st.top().second){
st.pop();
}
else{
break;
}
}
if (gay){
st.push(mp(x, y));
}
}
cout<<st.size();
}
