#include <bits/stdc++.h>
#include <atcoder/modint>

using namespace std;
using Mint = atcoder::modint998244353;

int main()
{
    int N, X;
    scanf("%d%d", &N, &X);
    vector<int> xx(N), yy(N);
    vector<Mint> y(N);
    for (int i = 0; i < N; i++)
        scanf("%d%d", &xx[i], &yy[i]);
    for (int i = 0; i < N; i++)
        if (xx[i] == X)
        {
            Mint ans = yy[i] * (N - 1);
            for (int j = 0; j < N; j++)
                if (j != i)
                {
                    Mint u = yy[j], d = 1;
                    for (int k = 0; k < N; k++)
                        if (k != j && k != i)
                        {
                            u *= X - xx[k];
                            d *= xx[j] - xx[k];
                        }
                    ans += u / d;
                }
            cout << ans.val() << endl;
            return 0;
        }
    for (int j = 0; j < N; j++)
    {
        Mint u = 1;
        Mint d = 1;
        for (int i = 0; i < N; i++)
            if (j != i)
            {
                u *= X - xx[i];
                d *= xx[j] - xx[i];
            }
        y[j] = Mint(yy[j]) * u / d;
    }
    vector<Mint> Xinv(N);
    for (int i = 0; i < N; i++)
        Xinv[i] = Mint(X - xx[i]).inv();

    Mint ans = 0;
    for (int i = 0; i < N; i++)
    {
        for (int j = 0; j < N; j++)
            if (j != i)
            {
                ans += y[j] * (xx[j] - xx[i]) * Xinv[i];
            }
    }
    printf("%d\n", ans.val());
}