#include <bits/stdc++.h>
using namespace std;
#define int long long
#define all(a) (a).begin(),(a).end()
#define rep(i, n) for(int i = 0; i < (n); i++)
#define rep1(i, n) for(int i = 1; i <= (n); i++)
const int mx = 2e5 + 9;
signed main(){
int n; cin >> n;
vector<int> l(n);
vector<int> r(n);
for (int i = 0; i < n; i++) {
cin >> l[i] >> r[i];
}
int dp[n + 1];
for (int i = 0; i <= n; i++) {
dp[i] = 1;
}
int ans = 0;
for (int i = 1; i < n; i++) {
// for (int j = 0; j < i - l[i]; j++) {
if (r[0] < i - 0) {
dp[i] = max(dp[i], dp[0] + 1);
}
if (r[1] < i - 1) {
dp[i] = max(dp[i], dp[1] + 1);
}
if (r[2] < i - 2) {
dp[i] = max(dp[i], dp[2] + 1);
}
ans = max(dp[i], ans);
}
cout << ans << endl;
return 0;
}
