import sys
N=int(sys.stdin.readline())
array=[]
for i in range(N):
array.append(list(map(int,sys.stdin.readline().split())))
array.sort(key=lambda x:(x[1],x[0]))
count =end_time=0
for i in range(N):
if end_time<=array[i][0]:
count+=1
end_time=array[i][1]
print(count)