#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
long long INF = 1e9;
const int N = 300031;
const int MAXN = 900000;
struct edge {
  int a, b, cap, flow;
};
int m;
int n, s, t, d[MAXN], ptr[MAXN], q[MAXN];
vector<edge> e;
vector<int> g[MAXN];
void add_edge(int a, int b, int cap) {
  edge e1 = {a, b, cap, 0};
  edge e2 = {b, a, 0, 0};
  g[a].push_back((int)e.size());
  e.push_back(e1);
  g[b].push_back((int)e.size());
  e.push_back(e2);
}
bool bfs() {
  int qh = 0, qt = 0;
  q[qt++] = s;
  memset(d, -1, n * sizeof d[0]);
  d[s] = 0;
  while (qh < qt && d[t] == -1) {
    int v = q[qh++];
    for (size_t i = 0; i < g[v].size(); ++i) {
      int id = g[v][i], to = e[id].b;
      if (d[to] == -1 && e[id].flow < e[id].cap) {
        q[qt++] = to;
        d[to] = d[v] + 1;
      }
    }
  }
  return d[t] != -1;
}
int dfs(int v, int flow) {
  if (!flow) return 0;
  if (v == t) return flow;
  for (; ptr[v] < (int)g[v].size(); ++ptr[v]) {
    int id = g[v][ptr[v]], to = e[id].b;
    if (d[to] != d[v] + 1) continue;
    int pushed = dfs(to, min(flow, e[id].cap - e[id].flow));
    if (pushed) {
      e[id].flow += pushed;
      e[id ^ 1].flow -= pushed;
      return pushed;
    }
  }
  return 0;
}
int dinic() {
  int flow = 0;
  for (;;) {
    if (!bfs()) break;
    memset(ptr, 0, n * sizeof ptr[0]);
    while (int pushed = dfs(s, INF)) flow += pushed;
  }
  return flow;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    int a, b;
    cin >> a >> b;
    if (a >= 1) add_edge(i, n + a, 1);
    if (b <= m) add_edge(i, n + m + b, 1);
  }
  for (int i = 2; i <= m; i++) {
    add_edge(n + i, n + i - 1, 10000000);
  }
  for (int i = 1; i < m; i++) {
    add_edge(n + m + i, n + m + i + 1, 1000000);
  }
  for (int i = 1; i <= m; i++) {
    add_edge(n + i, n + m + m + i, 1);
    add_edge(n + m + i, n + m + m + i, 1);
  }
  for (int i = 1; i <= n; i++) {
    add_edge(0, i, 1);
  }
  for (int i = 1; i <= m; i++) {
    add_edge(n + m + m + i, n + m + m + m + 1, 1);
  }
  s = 0;
  t = n + m + m + m + 1;
  int ans = n;
  n = t + 1;
  int res = dinic();
  cout << ans - res << endl;
  cin.get();
  cin.get();
  return 0;
}
