#include <bits/stdc++.h>
using namespace std;
#define rep(i,a,n) for (int i=a;i<n;i++)
#define per(i,a,n) for (int i=n-1;i>=a;i--)
#define pb push_back
#define eb emplace_back
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define fi first
#define se second
#define SZ(x) ((int)(x).size())
typedef vector<int> VI;
typedef basic_string<int> BI;
typedef long long ll;
typedef pair<int,int> PII;
typedef double db;
mt19937 mrand(random_device{}()); 
const ll mod=1000000007;
int rnd(int x) { return mrand() % x;}
ll powmod(ll a,ll b) {ll res=1;a%=mod; assert(b>=0); for(;b;b>>=1){if(b&1)res=res*a%mod;a=a*a%mod;}return res;}
ll gcd(ll a,ll b) { return b?gcd(b,a%b):a;}
// head

const int N=201000;
typedef __int128_t i128;
struct point {
	ll x,y;
	point() {}
	point(ll x,ll y):x(x),y(y) {} 
};
bool operator < (const point &a, const point &b) {
	return a.x<b.x||(a.x==b.x&&a.y<b.y);
}
vector<point> pt;
int h,t,q[N];
bool cmp(const point &a,const point &b,const point &c) {
	// b在c上面，严格上凸壳
	if (b.x==c.x) return 1;
	return (i128)(b.y-a.y)*(c.x-a.x)<(i128)(b.x-a.x)*(c.y-a.y);
}
void build(vector<point> &pt) {
	vector<int> q;
	sort(all(pt));
	rep(i,0,SZ(pt)) {
		while (SZ(q)>=2&&cmp(pt[q[SZ(q)-2]],pt[q[SZ(q)-1]],pt[i])) q.pop_back();
		q.push_back(i);
	}
	if (SZ(q)>=2&&pt[q[0]].x==pt[q[1]].x) q.erase(q.begin());
	vector<point> qt(SZ(q));
	rep(i,0,SZ(q)) qt[i]=pt[q[i]];
	pt=qt;
}
ll gao(point a,ll T) { return a.x*T+a.y;}
ll query(ll T) {
	while (t>h&&gao(pt[q[t]],T)<gao(pt[q[t-1]],T)) t--;
	return gao(pt[q[t]],T);
}
ll floordiv(ll a,ll b) {
	if (a>=0) return a/b;
	if (a%b==0) return a/b;
	return a/b-1;
}
ll ceildiv(ll a,ll b) {
	if (a<=0) return a/b;
	if (a%b==0) return a/b;
	return a/b+1;
}
ll f1[N],f2[N];
i128 eval(vector<point> pt) {
	build(pt);
	rep(i,1,SZ(pt)) {
		f1[i-1]=floordiv(pt[i].y-pt[i-1].y,pt[i].x-pt[i-1].x);
		f2[i-1]=ceildiv(pt[i].y-pt[i-1].y,pt[i].x-pt[i-1].x);
	}
	i128 cc=0;
	for (int l=0;l<SZ(pt)-1;l++) {
		int r=l;
		while (r<SZ(pt)-1&&f1[l]==f1[r]&&f2[l]==f2[r]) {
			r++;
		}
		ll x1=pt[l].x,y1=pt[l].y,x2=pt[r].x,y2=pt[r].y;
		ll k=f1[l];
		ll x3=x1+(y2-y1)-k*(x2-x1),y3=y1+(k+1)*(x3-x1);
		cc+=(i128)(y1+y3)*(x3-x1+1)/2+(i128)(y2+y3)*(x2-x3+1)/2-y3;
		if (l>0) cc-=y1;
		//printf("? (%lld,%lld) (%lld,%lld) mid : (%lld,%lld) %lld\n",x1,y1,x2,y2,x3,y3,(ll)cc);
		l=r-1;
	}
	return cc;
}
int n,m;
point p[N];

i128 eval(int px) {
	vector<point> pt;
	ll mv=-(1ll<<60);
	auto c2=[&](ll x) { return x*(x+1)/2; };
	rep(i,0,n) {
		if (p[i].x<=px) pt.pb(point(p[i].x,p[i].y+c2(px-p[i].x)));
		else pt.pb(point(p[i].x,p[i].y+c2(p[i].x-px-1)));
	}
	for (auto [x,y]:pt) mv=max(mv,y);
	pt.pb(point(px,mv)); sort(all(pt));
	i128 w=eval(pt);
	w-=(i128)px*(px+1)*(px+2)/6;
	w-=(i128)(m-px)*(m-px-1)*(m-px+1)/6;
	return w;
}
int main() {
	scanf("%d%d",&n,&m);
	//pt.pb(point(0,0));
	p[0]=point(0,0);
	rep(i,1,n+1) {
		ll x,y;
		scanf("%lld%lld",&x,&y);
		p[i]=point(x,y);
		//pt.pb(point(x,y));
	}
	p[n+1]=point(m,0);
	n+=2;
	int lo = -1, hi = m;
	while (hi - lo > 1){
	    int mid = (hi + lo)>>1;
	    if (eval(mid) < eval(mid + 1)) 
	         hi = mid;
	    else 
	         lo = mid; 
	}
	printf("%lld\n",(ll)(eval(lo+1)%998244353));
}