n,m=map(int,input().split())
a=0
B=[[] for i in range(m+1)]
for i in range(n):
	b,c=map(int,input().split())
	B[b].append(c)
for i in range(n):
	f=0
	for j in range(m+1):
		if i in B[j]:
			if f:B[f]+=B[j];B[j]=[];a+=1
			else:f=j
print(a)