// what is matter? never mind. 
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
#define ull unsigned long long
#define int long long
using namespace std;
inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;
 
#define maxn 4000005
#define inf 0x3f3f3f3f

struct bit{
	vector<int>tr;
	int n;
	void init(int N){n=N,tr=vector<int>(N+1,0);}
	void add(int x,int y){for(;x<=n;x+=x&-x)tr[x]+=y;}
	int ask(int x){
		int s=0;
		for(;x;x^=x&-x)s+=tr[x];
		return s;
	}
	void down(){For(i,1,n)tr[i]+=tr[i^(i&-i)];}
}tr;

int n,m,L;
int t[maxn],k;
struct node{
	int l,r,op,id;
}a[maxn];

int sum,res;
int val[maxn],s1[maxn],s2[maxn];

int st[maxn],tp;

signed main()
{
	n=read(),L=read();
	For(i,1,n){
		int l=read(),r=read();
		if(l<r) a[++m]={l,r,1,i},a[++m]={l+L,r+L,0,i};
		else a[++m]={l,r+L,1,i};
	}
	For(i,1,m) t[++k]=a[i].l,t[++k]=a[i].r;
	sort(t+1,t+k+1),k=unique(t+1,t+k+1)-t-1;
	#define V(x) lower_bound(t+1,t+k+1,x)-t
	For(i,1,m) a[i].l=V(a[i].l),a[i].r=V(a[i].r);
	sort(a+1,a+m+1,[&](node x,node y){
		return x.l<y.l;
	});
//	For(i,1,m)cout<<a[i].l<<" "<<a[i].r<<" "<<a[i].id<<"\n";
	tr.init(k);
	int all=0;
	For(i,1,m){
		val[a[i].id]+=all-tr.ask(a[i].r);
		if(a[i].op) tr.add(a[i].r,1),++all;
	}
	For(i,1,n)sum+=val[i];
//	cout<<"sum "<<sum<<"\n";
	tr.init(k);
	Rep(i,m,1){
		if(a[i].op) val[a[i].id]-=tr.ask(a[i].r);
		tr.add(a[i].r,1);
	}
//	For(i,1,n)cout<<val[i]<<" \n"[i==n];
	sort(val+1,val+n+1);
	For(i,1,n)s1[i]=s1[i-1]+val[i]*2,s2[i]=s2[i-1]-val[n-i+1]*2;
//	For(i,0,n)
//		For(j,0,n-i)
//			res=min(res,2*i*j+i*(n-i)+j*(n-j)+s1[i]+s2[j]);
	For(i,1,n)s1[i]+=i*(n-i),s2[i]+=i*(n-i);
	
	auto slope=[&](int i,int j){
		return 1.0l*(s2[i]-s2[j])/(j-i);
	};
	For(i,0,n){
		while(tp>=2 && slope(st[tp-1],st[tp])<=slope(st[tp],i))--tp;
		st[++tp]=i;
	}
	auto F=[&](int i,int j){
		return 2*i*j+s1[i]+s2[j];
	};
	int j=1;
	Rep(i,n,0){
		while(j<tp && F(i,st[j])>=F(i,st[j+1]))++j;
		res=min(res,F(i,st[j]));
	}
	cout<<res+sum;
	return 0;
}
/*

*/