n,m = map(int,input().split())
l = [set() for i in range(n+1)]
for i in range(n):
    b,c = map(int,input().split())
    l[c].add(b)

ans = 0
for i in range(1,n+1):
    if len(l[i]) <= 1:
        continue
    ans += len(l[i])-1
print(ans)