1931번

1931

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

bool compare(pair<int, int> a, pair<int, int> b) {
	if (a.second == b.second) return a.first < b.first;
	return a.second < b.second;
}

int solution(vector<pair<int, int>> v) {
	int end = v[0].second;
	int cnt = 1;

	for (int i = 1; i < v.size(); i++) {
		if (end <= v[i].first) {
			cnt++;
			end = v[i].second;
		}
	}
	return cnt;
}

int main() {
	int n;
	vector<pair<int,int>> v;
	cin >> n;
	for (int i = 0; i < n; i++) {
		int a, b;
		cin >> a >> b;
		v.push_back(make_pair(a, b));
	}

	sort(v.begin(), v.end(), compare);
	cout << solution(v);
}