#define REP(i, n) for(int i = 0; i < n; i ++)
#define REPL(i,m, n) for(int i = m; i < n; i ++)
#define FOREACH(it, l) for (auto it = l.begin(); it != l.end(); it++)
#define SORT(arr) sort(arr.begin(), arr.end())
#define LSOne(S) ((S)&-(S))
#define M_PI 3.1415926535897932384
#define INF 999999999
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef pair<int, int> ii;
typedef vector<ii> vii;
typedef long long ll;
typedef vector<ll> vll;
typedef vector<vll> vvll;
typedef double ld;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
int n;cin>>n;
vii arr;
int prev = -1;
REP(i, n) {
int x,y;cin>>x>>y;
if (x== prev) {
arr.back().second = max(arr.back().second, y);
} else {
arr.push_back({x,y});
}
prev = x;
}
int sze = arr.size();
bool covered[sze];
memset(covered, 0, sizeof(covered));
int prevOffset = -1;
REP(i, sze) {
auto [x,y] = arr[i];
int cur = x+y;
if (cur <= prevOffset) {
covered[i] = true;
}
prevOffset = max(cur, prevOffset);
}
prevOffset = -1;
for (int i = sze-1; i >=0; i--) {
auto [x,y] = arr[i];
int dx = 1e9 - x;
int cur = dx + y;
if (cur <= prevOffset) {
covered[i]= true;
}
prevOffset = max(cur, prevOffset);
}
int tot = sze;
REP(i, sze) {
if (covered[i]) tot--;
}cout<<tot;
}
