#include <stdio.h>
#include <limits.h>

#define MAXN 10000
#define DEBUG 1

int r[ MAXN ], l[ MAXN ], n, selected;

void read_input() {
	int i;

	scanf( "%d", &n );
	for ( i = 0; i < n; i++ )
		scanf( "%d %d", &l[ i ], &r[ i ] );
}

void search() {
	int x, i, ci, vi, j, cj, vj;
	x = 0;

	for (;;) {
		i = -1; vi = INT_MAX;
		for ( ci = 0; ci < n; ci++ ) {	
			if ( x <= l[ ci ] )
				if ( r[ ci ] < vi ) {
					i = ci;
					vi = r[ ci ]; 
				}
		}
		if ( i < 0 ) break;
		j = -1; vj = -1;
		for ( cj = 0; cj < n; cj++ ) {
			if ( x <= l[ cj ] && l[ cj ] <= r[ i ] )
				if ( r[ cj ] > vj ) {
					j = cj;
					vj = r[ cj ];
				} 
		}
		if ( DEBUG ) fprintf( stderr, "%d %d\n", l[ j ], r[ j ] );
		selected++;
		x = r[ j ] + 1;
	}
	
}

int main() {
#ifdef EVAL
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
	read_input();
	search();
	printf( "%d\n", selected );
	return 0;
}