#include<iostream>
using namespace std;
int main(){
	int n,i,j,k,pos,s[1000],f[1000];
	cin>>n;
	for(i = 0;i < n;i++){
		cin>>s[i]>>f[i];
	}
	for(i = 0;i < n - 1;i++){
		for(j = 0;j < n - 1 - i;j++){
			if(f[j] > f[j + 1]){
				k = s[j];s[j] = s[j + 1];s[j + 1] = s[j];
				k = f[j];f[j] = f[j + 1];f[j + 1] = f[j];
			}
		}
	}
	k = 0;
	pos = -1;
	for(i = 0; i <= n;i++){
		if(pos <= s[i]){
			pos = f[i];
			k++;
		}
	} 
	cout<<k;
	return 0;
}