#pragma GCC optimize("O3")
#include<bits/stdc++.h> 
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
template<class T> using V=vector<T>; 
#define fi first
#define se second
#define all(v) (v).begin(),(v).end()
const ll inf=(1e18);
const ll mod=998244353;
// const ll mod=1000000007;
const vector<int> dy={-1,0,1,0},dx={0,-1,0,1};
ll GCD(ll a,ll b) {return b ? GCD(b,a%b):a;}
ll LCM(ll c,ll d){return c/GCD(c,d)*d;}
struct __INIT{__INIT(){cin.tie(0);ios::sync_with_stdio(false);cout<<fixed<<setprecision(20);}} __init;
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
template<class T>void debag(const vector<T> &a){cerr<<"debag :";for(auto v:a)cerr<<v<<" ";cerr<<"\n";}
template<class T>void print(const vector<T> &a){for(auto v:a)cout<<v<<" ";cout<<"\n";}
struct mint{
using ull=unsigned long long int;
ull v;
mint(ll vv=0){s(vv%mod+mod);}
mint& s(ull vv){
v=vv<mod?vv:vv-mod;
return *this;
}
//オーバーロード
mint operator-()const{return mint()-*this;}//mint型にキャスト
mint&operator+=(const mint&val){return s(v+val.v);}
mint&operator-=(const mint&val){return s(v+mod-val.v);}
mint&operator*=(const mint&val){
v=ull(v)*val.v%mod;
return *this;
}
mint&operator/=(const mint&val){return *this*=val.inv();}
mint operator+(const mint&val){return mint(*this)+=val;}
mint operator-(const mint&val){return mint(*this)-=val;}
mint operator*(const mint&val){return mint(*this)*=val;}
mint operator/(const mint&val){return mint(*this)/=val;}
mint pow(ll n)const{
mint res(1),x(*this);
while(n){
if(n&1)res*=x;
x*=x;
n>>=1ll;
}
return res;
}
mint inv()const{return pow(mod-2);}
//拡張ユークリッドの互除法
/* mint inv()const{
int x,y;
int g=extgcd(v,mod,x,y);
assert(g==1);
if(x<0)x+=mod;
return mint(x);
}*/
friend ostream& operator<<(ostream&os,const mint&val){
return os<<val.v;
}//出力
bool operator<(const mint&val)const{return v<val.v;}
bool operator==(const mint&val)const{return v==val.v;}
bool operator>(const mint&val)const{return v>val.v;}
};
mint dp[200005][2][2]={};
int main(){
      int n;
      cin>>n;
      string s;
      cin>>s;
      dp[0][0][0]=mint(1);
      for(int i=0;i<n;i++){
            int c=(s[i]-'a');
            for(int j=0;j<2;j++){
                  for(int k=0;k<=(j?25:c);k++){
                        for(int r=0;r<2;r++){
                              if(r==1&&k==0)continue;
                              dp[i+1][(r||k==0)][(j||c>k)]+=dp[i][r][j];
                        }
                  }
            }
      }
      cout<<dp[n][1][1]<<"\n";
}