n=int(input())
ls=[]
for i in range(1,n+1):
    x=input().split()
    x[0]=int(x[0])
    x[1]=int(x[1])
    ls.append(x)
ls.sort(key=lambda x:x[1])
s=0
ans=0
for x in ls:
    if x[0]>=s:
        ans+=1
        s=x[1]
print(ans)