hdu2037

#include<iostream>//left<right,按结束时间早排序
#include<algorithm>
using namespace std;
struct play{
	int left,right;
}p[105];
bool compare (play a,play b){
	return a.right <b.right;
}
int main(){
	int n;
	while(cin>>n&&n){
		for(int i=0;i<n;i++)
		cin>>p[i].left>>p[i].right;
		sort(p,p+n,compare);
		int sum=1;
		int r=p[0].right;
		for(int i=1;i<n;i++){
			if(p[i].left>=r){
				sum++;
			r=p[i].right;
			}
			
		}
		cout<<sum<<endl;
	}
	
	return 0;
}