(정답코드 참조)
import sys
N = int(sys.stdin.readline())
arr = [[0, 0] for i in range(N)]
for i in range(N):
a, b = map(int, sys.stdin.readline().split())
arr[i][0] = a
arr[i][1] = b
arr = sorted(arr, key=lambda a: a[0])
arr = sorted(arr, key=lambda a: a[1])
count = 1
idx = arr[0][1]
for i in range(1, N, 1):
if idx <= arr[i][0]:
idx = arr[i][1]
count += 1
print(count)