#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
bool bo[200020] = { false };
vector<pair<int, int>> vec;
int main() {
	long long n, m;
	cin >> n >> m;
	for (int i = 0; i < n; i++) {
		int b, c;
		cin >> b >> c;
		vec.emplace_back(make_pair(c, b));
	}
	sort(vec.begin(), vec.end());
	int ans = 0;
	for (int i = 1; i < n; i++){
		if (vec[i - 1].first == vec[i].first) {
			if (!bo[vec[i].second] && vec[i - 1].second != vec[i].second) {
				bo[vec[i].second] = true;
				ans++;
			}
		}
	}
	cout << ans << endl;
}