#include <bits/stdc++.h>
using namespace std;
#define rep(i,N) for(int i=0,i##_max=(N);i<i##_max;++i)
#define repp(i,l,r) for(int i=(l),i##_max=(r);i<i##_max;++i)
#define per(i,N) for(int i=(N)-1;i>=0;--i)
#define perr(i,l,r) for(int i=r-1,i##_min(l);i>=i##_min;--i)
#define all(arr) (arr).begin(), (arr).end()
#define SP << " " <<
#define SPF << " "
#define SPEEDUP cin.tie(0);ios::sync_with_stdio(false);
#define MAX_I INT_MAX //1e9
#define MIN_I INT_MIN //-1e9
#define MAX_UI UINT_MAX //1e9
#define MAX_LL LLONG_MAX //1e18
#define MIN_LL LLONG_MIN //-1e18
#define MAX_ULL ULLONG_MAX //1e19
  typedef long long ll;
  typedef pair<int,int> PII;
  typedef pair<char,char> PCC;
  typedef pair<ll,ll> PLL;
  typedef pair<char,int> PCI;
  typedef pair<int,char> PIC;
  typedef pair<ll,int> PLI;
  typedef pair<int,ll> PIL; 
  typedef pair<ll,char> PLC; 
  typedef pair<char,ll> PCL; 

inline void YesNo(bool b){ cout << (b?"Yes" : "No") << endl;}
inline void YESNO(bool b){ cout << (b?"YES" : "NO") << endl;}
inline void Yay(bool b){ cout << (b?"Yay!" : ":(") << endl;}

int main(void){
  SPEEDUP
  cout << setprecision(15);
  int N;cin >> N;
  string s;cin >> s;
  map<pair<string,string>,int> mp;
  rep(n,1<<N){
    string t,u;
    rep(i,N){
      if((n>>i)&1) t.push_back(s[i]);
      else u.push_back(s[i]);
    }
    ++mp[make_pair(t,u)];
  }

  reverse(all(s));
  ll ans = 0;
  rep(n,1<<N){
    string t,u;
    rep(i,N){
      if((n>>i)&1) t.push_back(s[i]);
      else u.push_back(s[i]);
    }
    if(mp.count(make_pair(t,u))) ans += mp[make_pair(t,u)];
  }
  cout << ans << endl;
  return 0;
}

#include<bits/stdc++.h>
typedef long long int ll;
using namespace std;

int main() {
  const ll M = 998244353;
  ll N, ans = 1;
  cin >> N;
  vector<ll> d;
  vector<ll> cnt(N, 0);
  for (ll i = 0; i < N; i++) {
    ll x;
    cin >> x;
    if (i == 0) {
      if (x != 0) ans = 0;
    } else {
      d.push_back(x);
    }
    cnt[x]++;
  }
  for (auto x : d) {
    if (x > 0) ans *= cnt[x-1];
    else ans = 0;
    ans %= M;
  }
  cout << ans << endl;
  return 0;
}
