#pragma GCC optimize("Ofast")
#pragma GCC target("avx,avx2,fma")
#pragma GCC optimization ("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
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;
n = readInt();
int pref[n], suff[n];
for (int i = 0; i < n; i++) {
int x, y;
x = readInt();
y = readInt();
pref[i] = x + y;
suff[i] = y - x;
if (i > 0)
pref[i] = max(pref[i], pref[i - 1]);
}
int ans = 0;
for (int i = n - 1; i >= 0; i--) {
ans += ((i == 0) || pref[i] > pref[i - 1]) && ((i == n - 1) || suff[i] > suff[i + 1]);
if (i != n - 1)
suff[i] = max(suff[i], suff[i + 1]);
}
cout << ans << endl;
return 0;
}
