#include <bits/stdc++.h>
using namespace std;
using LL = long long;

const int mxn = 2e5 + 10;

int n;

struct node {
	int R, r;
	bool operator < (const node &rhs) const {
		return R == rhs.R ? r > rhs.r : R > rhs.R;
	}
} a[mxn];

multiset<node> s;

int main() {
	ios::sync_with_stdio(false);
	cin >> n;
	for (int i = 1; i <= n; ++i) {
		cin >> a[i].r >> a[i].R;
		s.insert(a[i]);
	}
	int ans = -1;
	while (!s.empty()) {
		++ans;
		node x = *begin(s);
		s.erase(begin(s));
		for (auto it = s.lower_bound({ x.r, INT_MAX }); it != end(s);) {
			assert(x.r >= it -> R);
			// printf("x = (%d, %d), it = (%d, %d)\n",
			// x.R, x.r, it -> R, it -> r);
			x = *it;
			s.erase(it);
			it = s.lower_bound({ x.r, INT_MAX });
		}
	}
	cout << ans << "\n";
	return 0;
}