#include <iostream>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstring>
#include <string>
#include <math.h>
using namespace std;
typedef long long ll;
typedef double D;
typedef pair<int,int> P;
#define M 1000000007
#define F first
#define S second
#define PB push_back
#define INF 100000000000000000
int n,m,ans,seg[1<<19],la[1<<19];
P c[200005];
void lazy(int l,int r,int k){
    seg[k]+=la[k];
    if(l!=r){
        la[k*2+1]+=la[k];
        la[k*2+2]+=la[k];
    }
    la[k]=0;
}
void up(int a,int b,int l,int r,int k,int x){
    lazy(l,r,k);
    if(r<a||b<l)return;
    if(a<=l&&r<=b){
        la[k]+=x;
        lazy(l,r,k);
        return;
    }
    up(a,b,l,(l+r-1)/2,k*2+1,x);
    up(a,b,(l+r+1)/2,r,k*2+2,x);
    seg[k]=max(seg[k*2+1],seg[k*2+2]);
}
int que(int a,int b,int l,int r,int k){
    lazy(l,r,k);
    if(r<a||b<l)return 0;
    if(a<=l&&r<=b)return seg[k];
    return max(que(a,b,l,(l+r-1)/2,k*2+1),que(a,b,(l+r+1)/2,r,k*2+2));
}
int main(void){
    cin>>n>>m;
    ans=max(ans,n-m);
    for(int i=0;i<n;i++)scanf("%d%d",&c[i].F,&c[i].S);
    sort(c,c+n);
    for(int i=1;i<=m;i++)up(i,i,0,(1<<18)-1,0,-(m-i+1));
    for(int i=0;i<n;i++){
        up(1,c[i].S,0,(1<<18)-1,0,1);
        ans=max(ans,que(c[i].F+1,m+1,0,(1<<18)-1,0)-c[i].F);
    }
    printf("%d\n",ans);
}
