import sys
input = sys.stdin.readline
from collections import *

N, M = map(int, input().split())
slime = defaultdict(list)

for _ in range(N):
    b, c = map(int, input().split())
    slime[c].append(b)

ans = 0

for v in slime.values():
    ans += len(set(v))-1

print(ans)