#include<bits/stdc++.h>
using namespace std;
 
const int N=1e5+10;
struct node{
    int a,b;
    bool operator<(const node&w)const {
        return b<w.b;}
}range[N];

int main(){
    int n;
    cin>>n;
    int a,b;
    for(int i=0;i<n;i++){
        cin>>a>>b;
        range[i]={a,b};
    }
    sort(range, range+n);
    int s=-2e9,cnt=0;
    for(int i=0;i<n;i++){
        if(s<range[i].a){
            cnt++;
            s=range[i].b;
        }
    }
    cout<<cnt;
    return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N=1e5+10;

struct node{
    int a,b;
    bool operator<(const node&w)const{
        return b<w.b;
    }
}range[N];
int main(){
    ios::sync_with_stdio(0);
    cin.tie(0),cout.tie(0);
    int n;
    cin>>n;
    for(int i=0;i<n;i++){
        int a,b;
        cin>>a>>b;
        range[i]={a,b};
    }
    int res=0,s=-2e9;
    sort(range,range+n);
    for(int i=0;i<n;i++){
        if(range[i].a>s){
            s=range[i].b;
            res++;
        }
    }
    cout<<res;
    return 0;
    
}

#include<bits/stdc++.h>

using namespace std;

const int N = 100010;

int n;
int b[2 * N], idx;

int main() {
	cin >> n;
	for (int i = 0; i < n; i++) {
		int l, r;
		cin >> l >> r;
		b[idx++] = l * 2;
		b[idx++] = r * 2 + 1;//用奇偶性區(qū)分左右端點
	}
	sort(b, b + idx);
	int res = 1, t = 0;
	for (int i = 0; i < idx; i++) {
		if (b[i] % 2 == 0)t++;
		else t--;
		res = max(res, t);
	}
	cout << res;
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
const int N = 100010;
struct Range {
    int l, r;
    bool operator <(const  Range& w)const {
        return l < w.l;
    }
}range[N];
int n;
int main() {
    cin >> n;
    for (int i = 0; i < n; i++) {
        int l, r;
        cin >> l >> r;
        range[i] = { l,r };}
    sort(range, range + n);
    int res = 0,ed=-2e9;
    
    priority_queue<int, vector<int>, greater<int>>heap;
    for (int i = 0; i < n; i++) {
        auto r = range[i];
        if (heap.empty() || heap.top() >= r.l)heap.push(r.r);
        else {
            int t = heap.top();
            heap.pop();
            heap.push(r.r);
        }
    }
    cout << heap.size();
    return 0;
}

#include<bits/stdc++.h>

using namespace std;

const int N = 100010;
struct  Range {
	int l, r;
	bool operator <(const Range& w)const {
		return l < w.l;
	}
}range[N];

int main() {
	int n;
	int st, ed;
	cin >> st >> ed;
	cin >> n;
	for (int i = 0; i < n; i++) {
		int l, r;
		cin >> l >> r;
		range[i] = { l,r };

	}
	sort(range, range + n);
	int res = 0;
	bool sc = false;
	for (int i = 0; i < n; i++) {
		int j = i, r = -2e9;
		while (j < n && range[j].l <= st) {
			r = max(r, range[j].r);
			j++;
		}
		if (r < st) {
			res = -1;
			break;
		}
		res++;
		if (r >= ed) {
			sc = true;
			break;
		}
		i = j-1;
		st = r;
	}
	if (!sc)cout << -1;
	else cout << res;
	return 0;
}

#include<iostream>
#include<algorithm>
#include<queue>
#include<bits/stdc++.h>
using namespace std;

int main() {
	int n;
	cin>>n;
	priority_queue<int, vector<int>, greater<int>>heap;

	while (n--) {
		int x;
		cin >> x;
		heap.push(x);
	}
	int res = 0;
	while (heap.size() > 1) {
		int a = heap.top();
		heap.pop();
		int b = heap.top();
		heap.pop();
		int c = a + b;
		heap.push(c);
		res += c;
	}
	cout << res;
	return 0;
}

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

const int N = 100010;
int a[N];
int main() {
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	sort(a, a + n);
	int x=n;
	long long res=0;
	for (int i = 0; i < n; i++) {
		res += a[i] * (x - 1);
		x--;
	}
	cout << res;
	return 0;
}

#include <bits/stdc++.h>
using namespace std;
const int N=100100;
int a[N],n,i,ans,sum;
int main()
{
    cin>>n;
    for (i=1;i<=n;i++)
        cin>>a[i];
    sort(a+1,a+1+n);//排序
    int sm=a[n/2+1];//中位數(shù)
    for (i=1;i<=n;i++)
        ans=ans+abs(a[i]-sm);//統(tǒng)計和中位數(shù)之間的差
    cout<<ans;
    return 0;
}