#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint998244353;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001


int main(){
	
	int N,X;
	cin>>N>>X;
	
	vector<int> x(N),y(N);
	rep(i,N)cin>>x[i]>>y[i];
	vector<mint> V(N);
	int ind = -1;
	rep(i,N){
		V[i]  =X-x[i];
		if(V[i].val()!=0)V[i] = V[i].inv();
		else ind = i;
	}
	mint ans = 0;
	if(ind == -1){
		rep(i,N){
			mint P = 1,Q = 1;
			rep(j,N){
				if(i==j)continue;
				P *= X-x[j];
				Q *= x[i]-x[j];
			}
			P /= Q;
			Q = 0;
			rep(j,N){
				if(i==j)continue;
				mint t = x[i]-x[j];//X-x[j];
				t *= V[j];///= X-x[j];
				Q += t;
			}
			P *= Q;
			P *= y[i];
			ans += P;
		}
	}
	else{
		rep(i,N){
			if(i!=ind){
				
				mint P = 1,Q = 1;
				rep(j,N){
					if(j==ind||j==i)continue;
					P *= X-x[j];
					Q *= x[i]-x[j];
				}
				P /= Q;
				P *= y[i];
				ans += P;
			}
			else{
				mint P = 1,Q = 1;
				rep(j,N){
					if(i==j)continue;
					P *= X-x[j];
					Q *= x[i]-x[j];
				}
				P /= Q;
				Q = 0;
				rep(j,N){
					if(i==j)continue;
					mint t = x[i]-x[j];//X-x[j];
					t *= V[j];///= X-x[j];
					Q += t;
				}
				P *= Q;
				P *= y[i];
				ans += P;
				
			}
		}
		
	}
	
	cout<<ans.val()<<endl;
	
    return 0;
}