hdu 2037

#include<stdio.h>
#include<stdlib.h>
struct node{
	int st,end;
}se[105];
int cmp(const void *c,const void *d){
	struct node *a=(node*)c;
	struct node *b=(node*)d;
	if(a->st!=b->st) return a->st-b->st;
	else return a->end-b->end;
}
int main(){
	int t,i,temp,ant;
	while(scanf("%d",&t)){
		if(t==0) break;
		ant=1;
		for(i=0;i<t;i++)
		 	scanf("%d %d",&se[i].st,&se[i].end);
		qsort(se,t,sizeof(se[0]),cmp);
		temp=se[t-1].st;
		for(i=t-2;i>=0;i--)
			if(se[i].end<=temp) {
				temp=se[i].st;
				ant++;
			}
	printf("%d\n",ant);
	}
	return 0;	
}