题解

#include<bits/stdc++.h>
using namespace std;
struct ss{
    int s,e;
}a[100001];
bool cmp(ss aa,ss bb)
{
	return aa.e < bb.e;//越早结束越好
}
int main()
{
    int n;
    cin>>n;
    for(int i=1;i<=n;++i) cin>>a[i].s>>a[i].e;
    sort(a+1,a+1+n,cmp);
    int ans = a[1].e;
    int cnt=1;
    for(int i=2;i<=n;++i)
    {
		if(ans <= a[i].s)
        {
			cnt++;
            ans = a[i].e;
        }
    }
    cout<<cnt;
    
    return 0;
}