#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using Modint = atcoder::modint998244353;
istream& operator>>(istream& cin, Modint& x){
    int x_;
    cin >> x_;
    x = Modint::raw(x_);
    return cin;
}


int main(){
    int N;
    Modint X;
    cin >> N >> X;
    vector<pair<Modint, Modint>> P(N);
    for(auto& [x, y] : P) cin >> x >> y;
    if(auto p = find_if(P.begin(), P.end(), [&](auto p){ return p.first == X; }); p != P.end()){
        Modint ans = p->second * (N - 1);
        P.erase(p);
        for(auto [x0, y0] : P){
            pair<Modint, Modint> a = {1, 1};
            for(auto [x, y] : P) if(x != x0){
                a.first *= X - x;
                a.second *= x0 - x;
            }
            ans += a.first / a.second * y0;
        }
        cout << ans.val() << endl;
        return 0;
    }
    Modint ans = 0;
    for(auto [x0, y0] : P){
        Modint denom = 1, numer = 0;
        vector<Modint> l;
        for(auto [x, y] : P) if(x != x0){
            denom *= x0 - x;
            l.push_back(X - x);
        }
        vector<Modint> r(l.size());
        exclusive_scan(l.rbegin(), l.rend(), r.rbegin(), Modint{1}, multiplies<>{});
        exclusive_scan(l.begin(), l.end(), l.begin(), Modint{1}, multiplies<>{});
        int i = 0;
        for(auto [x, y] : P) if(x != x0){
            numer += l[i] * r[i] * (x0 - x);
            i++;
        }
        ans += numer / denom * y0;
    }
    cout << ans.val() << endl;
}