#include <iostream>
using namespace std;
struct qujian {
    long long st;
    long long ed;
};
int main() {
    long long a;
    cin >> a;
    qujian* jihe = new qujian[a];
    for (int i = 0; i < a; i++) cin >> jihe[i].st >> jihe[i].ed;
    for (int i = 0; i < a; i++)
        for (int j = i + 1; j < a; j++) {
            if (jihe[i].st == 0)
                break;
            else if (jihe[j].st == 0)
                continue;
            else if (jihe[i].ed >= jihe[j].st && jihe[i].st <= jihe[j].st && jihe[i].ed <= jihe[j].ed) {
                jihe[i].st = jihe[j].st;
                jihe[j].st = jihe[j].ed = 0;
            } else if (jihe[i].st < jihe[j].st && jihe[i].ed > jihe[j].ed) {
                jihe[i].st = jihe[j].st;
                jihe[i].ed = jihe[j].ed;
                jihe[j].st = jihe[j].ed = 0;
            } else if (jihe[i].ed >= jihe[j].ed && jihe[i].st > jihe[j].st && jihe[i].st <= jihe[j].ed) {
                jihe[i].ed = jihe[j].ed;
                jihe[j].st = jihe[j].ed = 0;
            }
        }
    long long b = 0;
    for (int i = 0; i < a; i++)
        if (jihe[i].st != 0)
            b++;
    cout << b;
    return 0;
}