30分求条

#include<bits/stdc++.h>
using namespace std;
int n,k;
struct node{
    int x,y;
}a[1005];
bool cmp(node &aa,node &bb){
    if(aa.x!=bb.x)return aa.x<bb.x;
    return aa.y>bb.y;
}
int main(){
    cin>>n>>k;
    for(int i=1;i<=k;i++){
    	cin>>a[i].x>>a[i].y;
    	if(a[i].x>a[i].y){
    		int t=a[i].x;
    		a[i].x=a[i].y;
    		a[i].y=t;
		}
	}
    if(k==0){
        cout<<1<<endl;
        return 0;
    }
    sort(a+1,a+1+k,cmp);
    int ans=0,pre=-1;
    for(int i=1;i<=k;i++){
        if(a[i].x>=pre){
            ans++;
            pre=a[i].y;
        }
        else pre=max(pre,a[i].y);
    }
    cout<<ans+1<<endl;
}