#include<cstdio>
#include<cctype>
#include <algorithm>
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
//#pragma GCC optimize("O3,unroll-loops,fast-math")
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//#define int long long
#define I128 //||is_same<T,__int128_t>::value||is_same<T,__uint128_t>::value
using namespace std;
//using namespace __gnu_pbds;
template<typename T>enable_if_t<is_integral<T>::value I128,void> readmain(T &x)
{
bool neg=false;int c=getchar();
for(;!isdigit(c);c=getchar())if(c=='-')neg=true;
for(x=0;isdigit(c);c=getchar())x=(T)(10*x+(c-'0'));
if(neg)x=-x;
}
template<typename T>T& read(T &x){readmain(x);return x;}
template<typename T,typename ...Tr>void read(T &x,Tr&... r){readmain(x);read(r...);}
constexpr int maxn = 1e7 + 1;
int a[maxn], b[maxn];
void solve(){
int n;
read(n);
int cnt = 0;
/*tree<
int,
null_type,
less_equal<int>,
rb_tree_tag,
tree_order_statistics_node_update> s;*/
int mn = 2000000001, mx = -2000000001;
for(int i = 1; i <= n; i++) {
int x, y;
read(x, y);
mx = max(mx, y + x);
a[i] = mx;
b[i] = x - y;
}
for(int i = n; i >= 1; i--) {
if(i == n) {
if(a[i] > a[i - 1]) {
cnt++;
}
}
else if(i == 1) {
if(mn > b[i]) {
cnt++;
}
}
else{
if(a[i] > a[i - 1] && mn > b[i]) {
cnt++;
}
}
mn = min(mn, b[i]);
}
printf("%d", cnt);
}
int main(){
//ios_base::sync_with_stdio(false);
//cin.tie(nullptr);
int tt = 1;
//cin >> tt;
while(tt--) {
solve();
}
}
