#include <bits/stdc++.h>
using namespace std;
bool mst;
namespace MF{
    #define int_64 int
    static const int maxn = 8e5 + 100;
    static const int maxm = 3e6 + 5e5 + 100;
    const int_64 Mxf = 1e9;
    struct E{int to, nxt;int_64 f;}e[maxm];
    int hd[maxn], cur[maxn], _te = 1;
    void add_edge(int u, int v, int_64 w = 1){
        e[++_te] = {v, hd[u], w};hd[u] = _te;  
        e[++_te] = {u, hd[v], 0};hd[v] = _te;
    }
    int nods, s, t;
    int_64 maxf = 0;
    int d[maxn];
    bool bfs(){
        for(int i = 0;i <= nods;i++) d[i] = 0, cur[i] = hd[i];
        queue<int> q;q.push(s);d[s] = 1;
        while(!q.empty()){
            int u = q.front();q.pop();
            for(int i = hd[u];i;i = e[i].nxt){
                int v = e[i].to;
                if(e[i].f && !d[v]){
                    d[v] = d[u] + 1;
                    q.push(v);
                    if(v == t) return 1;
                }
            }
        }
        return 0;
    }
    int_64 dfs(int u, int_64 flow){
        if(u == t) return flow;
        int_64 sum = 0;
        for(int &i = cur[u];i;i = e[i].nxt){
            int v = e[i].to;
            if(e[i].f && d[v] == d[u] + 1){
                int_64 gt = dfs(v, min(e[i].f, flow));
                e[i].f -= gt, e[i ^ 1].f += gt;
                sum += gt, flow -= gt;
            }
        }
        if(!sum) d[u] = 0;
        return sum;
    }
    void dinic(){
        while(bfs()) maxf += dfs(s, Mxf);
    }
}
using namespace MF;
int n, m;
const int N = 2e5 + 100;
int pf[N], sf[N];
bool med;
int main(){
    ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
    cin >> n >> m;nods = n + m;
    pf[1] = ++nods;add_edge(pf[1], n + 1);
    for(int i = 2;i <= m;i++){
        pf[i] = ++nods;
        add_edge(pf[i - 1], pf[i], Mxf);
        add_edge(pf[i], n + i);
    }
    sf[m] = ++nods;add_edge(sf[m], n + m);
    for(int i = m - 1;i >= 1;i--){
        sf[i] = ++nods;
        add_edge(sf[i + 1], sf[i], Mxf);
        add_edge(sf[i], n + i);
    }
    s = 0, t = ++nods;
    for(int i = 1;i <= n;i++){
        add_edge(s, i);
        int x, y;cin >> x >> y;
        if(x >= 1) add_edge(i, sf[x]);
        if(y <= m) add_edge(i, pf[y]);
    }
    for(int i = 1;i <= m;i++) add_edge(n + i, t);
    dinic();
    cout << n - maxf << endl;
    //cerr << fixed << setprecision(3) << 1.0 * (&mst - &med) / 1024.0 / 1024.0 << endl;
}