#include <bits/stdc++.h>
using namespace std;
const int maxn = 1e5 + 10, mod = 998244353;
int mu[maxn], n, m, l[51], r[51], prime[maxn], cnt;
bool is_composite[maxn];
int dp[maxn], pre[maxn];
int cal(int d) {
  int M = m / d;
  for (int i = 1; i <= M; i++) dp[i] = 0;
  dp[0] = 1;
  for (int i = 1; i <= n; i++) {
    int L = (l[i] + d - 1) / d, R = r[i] / d;
    if (L > R) return 0;
    pre[0] = dp[0];
    for (int j = 1; j <= M; j++) pre[j] = (pre[j - 1] + dp[j]) % mod;
    for (int j = 0; j <= M; j++) {
      dp[j] = (((j - L >= 0) ? pre[j - L] : 0) -
               ((j - R - 1 >= 0) ? pre[j - R - 1] : 0)) %
              mod;
    }
  }
  pre[0] = dp[0];
  for (int j = 0; j <= M; j++) pre[j] = (pre[j - 1] + dp[j]) % mod;
  return pre[M];
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) scanf("%d%d", &l[i], &r[i]);
  mu[1] = 1;
  for (int i = 2; i <= m; i++) {
    if (!is_composite[i]) {
      prime[++cnt] = i;
      mu[i] = mod - 1;
    }
    for (int j = 1; j <= cnt && i * prime[j] <= m; j++) {
      is_composite[i * prime[j]] = true;
      if (i % prime[j])
        mu[i * prime[j]] = (mod - mu[i]) % mod;
      else
        break;
    }
  }
  int ans = 0;
  for (int d = 1; d <= m; d++) {
    ans = (ans + 1LL * cal(d) * mu[d]) % mod;
  }
  cout << ans << '\n';
}
