#include <bits/stdc++.h>
using namespace std;
const int maxn = 6000000 + 5,mo=998244353;
int n;
namespace pam {
int sz, tot, last;
int cnt[maxn], ch[maxn][10], len[maxn], fail[maxn];
char s[maxn];

int node(int l) {  // ???????,??? l
  sz++;
  memset(ch[sz], 0, sizeof(ch[sz]));
  len[sz] = l;
  fail[sz] = cnt[sz] = 0;
  return sz;
}

void clear() {  // ???
  sz = -1;
  last = 0;
  s[tot = 0] = '$';
  node(0);
  node(-1);
  fail[0] = 1;
}

int getfail(int x) {  // ?????
  while (s[tot - len[x] - 1] != s[tot]) x = fail[x];
  return x;
}

void insert(char c,bool d) {  // ??
  s[++tot] = c;
  int now = getfail(last);
  if (!ch[now][c - '0']) {
    int x = node(len[now] + 2);
    fail[x] = ch[getfail(fail[now])][c - '0'];
    ch[now][c - '0'] = x;
  }
  last = ch[now][c - '0'];
	cnt[last]+=d;
}

int solve(){
	int ans=0;
	for(int i=sz;i>=0;i--) cnt[fail[i]]=(cnt[fail[i]]+cnt[i])%mo;
	for(int i=2;i<=sz;i++) if(len[i]<=n){
//		cout<<"#"<<len[i]<<" "<<cnt[i]<<endl;
		ans=(ans+(long long)len[i]*cnt[i]%mo*cnt[i])%mo;
	}
	return ans;
}
}  // namespace pam

char s[maxn];

int main() {
  pam::clear();
  scanf("%d",&n);
  scanf("%s", s + 1);
  for(int i=n+1;i<=2*n;i++) s[i]=s[i-n];
  for (int i = 1; i<=2*n; i++) {
    pam::insert(s[i],(i>n));
  }
  printf("%d\n", pam::solve());
  return 0;
}