from collections import Counter
n,m=map(int,input().split())
a=0
L=[[] for i in range(n+1)]
for i in range(n):
	b,c=map(int,input().split())
	L[c].append(b)
for l in L:
	x=Counter(l).most_common()
	if x:a+=len(x)-1
print(a)