from collections import defaultdict


def main():
    n, m = map(int, input().split())

    d = defaultdict(set)
    for _ in range(n):
        box, color = map(int, input().split())
        d[color].add(box)

    ans = 0
    for x in d.values():
        ans += len(x) - 1
    print(ans)


if __name__ == "__main__":
    main()