#include <bits/stdc++.h>
using namespace std;
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n; cin >> n;
pair<int,int> risa[n];
vector<pair<int,int>> zabijmnie;
for (int i = 0; i < n; i++)
cin >> risa[i].first >> risa[i].second;
if (n == 1)
cout << 1 << endl;
else {
int dp[n][2], odp = 0;
sort(risa,risa+n);
for (int i = 0; i < n; i++)
if (i == 0 || risa[i] != zabijmnie.back())
zabijmnie.push_back(risa[i]);
int m = zabijmnie.size();
for (int i = 0; i < m; i++)
risa[i] = zabijmnie[i];
if (m == 1)
cout << 1 << endl;
else {
dp[0][0] = risa[0].first+risa[0].second, dp[m-1][1] = risa[m-1].second-risa[m-1].first;
for (int i = 1; i < m; i++)
dp[i][0] = max(dp[i-1][0],risa[i].first+risa[i].second);
for (int i = m-2; i >= 0; i--)
dp[i][1] = max(dp[i+1][1],risa[i].second-risa[i].first);
if (risa[0].second-risa[0].first > dp[1][1])
odp++;
if (risa[m-1].first+risa[m-1].second > dp[m-2][0])
odp++;
for (int i = 1; i < m-1; i++)
if (risa[i].second-risa[i].first > dp[i+1][1] && risa[i].first+risa[i].second > dp[i-1][0])
odp++;
cout << odp << endl;
}
}
return 0;
}
