#include <algorithm>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <iostream>
#include <numeric>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <functional>
#include <iomanip>
using namespace std;
using ll = long long;

class range {private: struct I{int x;int operator*(){return x;}bool operator!=(I& lhs){return x<lhs.x;}void operator++(){++x;}};I i,n;
public:range(int n_):i({0}),n({n_}){}range(int i_,int n_):i({i_}),n({n_}){}I& begin(){return i;}I& end(){return n;}};

template<typename T, typename U> ostream& operator<<(ostream& os, const pair<T, U>& p){ return os << "{" << p.first << ", " << p.second << "}"; }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& obj) { os << "{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T> ostream& operator<<(ostream& os, const set<T>& obj) { os << "set{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }
template<typename T, typename U> ostream& operator<<(ostream& os, const map<T, U>& obj) { os << "map{"; for (const auto& e : obj) os << e << ", "; return os << "}"; }

#ifdef ONLINE_JUDGE
#define dump(expr) ;
#else
#define dump(expr) { cerr << "\033[33m#L" << __LINE__ << ": " << expr << "\033[39m" << endl; }
#endif

const ll mod = 998244353;
struct mint {
  ll x;
  mint(ll x_ = 0) : x((x_ % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) { if ((x += a.x) >= mod) x -= mod; return *this; }
  mint &operator-=(const mint &a) { if ((x += mod - a.x) >= mod) x -= mod; return *this; }
  mint &operator*=(const mint &a) { (x *= a.x) %= mod; return *this; }
  mint operator+(const mint &a) const { mint res(*this); return res += a; }
  mint operator-(const mint &a) const { mint res(*this); return res -= a; }
  mint operator*(const mint &a) const { mint res(*this); return res *= a; }
  mint pow(ll t) const { if (!t) return 1; mint a = pow(t >> 1); a *= a; if (t & 1) a *= *this; return a; }
  mint inv() const { return pow(mod - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const { mint res(*this); return res /= a; }
  friend ostream &operator<<(ostream &os, const mint &m) { os << m.x; return os; }
  friend istream &operator>>(istream &is, mint &m) { is >> m.x; return is; }
};

namespace solver {

int n;
mint x0;
vector<mint> xs, ys;

void read() {
  cin >> n >> x0;
  xs.resize(n);
  ys.resize(n);
  for (int i : range(n)) cin >> xs[i] >> ys[i];
}

mint f2(int i, int j, mint x) {
  mint ret = 1;
  for (int k : range(n)) if (k != i && k != j) ret *= x - xs[k];
  return ret;
}

void naive() {
  {
    mint tot = 0;
    for (int j : range(n))
    for (int i : range(n)) if (j != i) {
      tot += ys[j] * f2(i, j, x0) / f2(i, j, xs[j]);
    }
    dump(tot);
  }
  {
    mint tot = 0;
    for (int j : range(n)) {
      for (int i : range(n)) if (j != i) {
        tot += ys[j] * f2(j, j, x0) / (x0 - xs[i]) / f2(i, j, xs[j]);
      }
    }
    dump(tot);
  }
  {
    mint tot = 0;
    for (int j : range(n)) {
      for (int i : range(n)) if (j != i) {
        tot += ys[j] * f2(j, j, x0) * (xs[j] - xs[i]) / (x0 - xs[i]) / f2(j, j, xs[j]);
      }
    }
    dump(tot);
  }
}

mint f(int i, mint x) {
  mint ret = 1;
  for (int j : range(n)) if (j != i) ret *= x - xs[j];
  return ret;
}

ll run() {
  for (int p : range(n)) if (xs[p].x == x0.x) {
    mint ret = 0;
    for (int i : range(n)) if (i != p) ret += ys[p];
    for (int i : range(n)) if (i != p) ret += ys[i] * f2(i, p, x0) / f2(i, p, xs[i]);
    return ret.x;
  }

  vector<mint> fs(n), fs0(n);
  for (int j : range(n)) {
    fs[j] = f(j, xs[j]);
    fs0[j] = f(j, x0);
  }
  mint ret = 0;

  dump(fs);

  for (int j : range(n)) {
    mint tot = 0;
    for (int i : range(n)) if (i != j) tot += (xs[j] - xs[i]) / (x0 - xs[i]);
    ret += ys[j] * fs0[j] / fs[j] * tot;
  }
  return ret.x;
}

}

int main(int argc, char** argv) {
  cout << fixed << setprecision(12);
  int testcase = 1;
  if (argc > 1) testcase = atoi(argv[1]);
  while (testcase--) {
    solver::read();
  }
  // solver::naive();
  cout << solver::run() << endl;
}