#include <bits/stdc++.h>
using namespace std;
long long mod, n, m, a[200005], b[200005], kq, vt1, vt2, l, r, mid, mn[200005];
map<int, bool> mp;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  mod = 998244353;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    mp[a[i]] = true;
  }
  for (int i = 1; i <= m; ++i) {
    cin >> b[i];
    if (!mp[b[i]]) {
      cout << 0;
      return 0;
    }
  }
  for (int i = 1; i <= n; ++i) {
    if (a[i] < b[1]) {
      cout << 0;
      return 0;
    }
    if (a[i] == b[m]) vt1 = i;
  }
  for (int i = n; i > vt1; --i)
    if (a[i] < b[m]) {
      cout << 0;
      return 0;
    }
  mn[n] = a[n];
  for (int i = n - 1; i > 0; --i) mn[i] = min(a[i], mn[i + 1]);
  kq = 1;
  for (int i = 1; i < m; ++i) {
    l = 1;
    r = n - 1;
    while (l <= r) {
      mid = (l + r) / 2;
      if (mn[mid + 1] >= b[i + 1]) {
        vt1 = mid;
        r = mid - 1;
      } else
        l = mid + 1;
    }
    l = 1;
    r = n - 1;
    while (l <= r) {
      mid = (l + r) / 2;
      if (mn[mid + 1] > b[i + 1])
        r = mid - 1;
      else {
        vt2 = mid;
        l = mid + 1;
      }
    }
    kq = kq * max(0LL, vt2 - vt1 + 1) % mod;
    ;
  }
  cout << kq;
  return 0;
}
