C++ :

#include <cstdio>

#define  maxn  20001

int n , i , j , k , ans ;
int l[maxn] = {0} , r[maxn] = {0} ;
bool v[maxn] = {0} ;

void up(int ll , int rr , int t ) {
	//不知所云的浮水法 
	if (v[i]) return ;
	while (t<=n && (l[t]>=rr || r[t]<=ll)) t ++ ;
	if (t > n) {
		ans ++ ;
		v[i] = true ;
	}
	if (ll<l[t] && rr>l[t]) up(ll,l[t],t+1) ;
	if (ll<r[t] && rr>r[t]) up(r[t],rr,t+1) ;
}

int main() {
	scanf("%d", &n ) ;
	for (i = 1 ; i <= n ; i ++ ) scanf("%d%d", &l[i] , &r[i] ) ;
	for (i = n-1 ; i > 0 ; i -- ) up(l[i],r[i],i+1) ;
	ans ++ ;
	printf("%d\n", ans ) ;
	return 0 ;
}