#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
template<typename T> bool chmin(T& a, T b){if(a > b){a = b; return true;} return false;}
template<typename T> bool chmax(T& a, T b){if(a < b){a = b; return true;} return false;}
const long long mod=998244353;
const long long mod2=469762049;
const long long mod100=1000000007;
struct MATH{
    vector<ll>factorial;//階乗データ
    vector<ll>factorial_inv;
    void factorial_init(ll N,ll m){//階乗を入れる
        assert(N>=0);
        factorial.assign(N+1,0);
        factorial_inv.assign(N+1,0);
        ll p=1;
        factorial[0]=1;
        for(int i=1;i<=N;i++){
            p=(p*i)%m;
            factorial[i]=p;
        }
        factorial_inv[N]=modinv(factorial[N],m);
        for(int i=N-1;i>=0;i--){
            factorial_inv[i]=(factorial_inv[i+1]*(i+1))%m;
        }
        return;
    }
    ll power(ll a,ll b,ll m){//a^b
        assert(b>=0);
        a%=m;
        if(a<0) a+=m;
        ll p=a,Answer=1;
        for(ll i=0;i<60;i++){
            ll wari=(1LL<<i);
            if((b/wari)%2==1){
                Answer=(Answer*p)%m;
            }
            p=(p*p)%m;
        }
        return Answer;
    }
    ll Division(ll a,ll b,ll m){//a/b
        return (a*power(b,m-2,m))%m;
    }
    ll modinv(ll x,ll m){//逆元
        return power(x,m-2,m);
    }
    ll comb(ll n,ll r,ll m){//nCrを求める(factorial必要)
        if(n<0 || r<0 || n-r<0) return 0;
        ll res=factorial[n];
        res=(res*factorial_inv[r])%m;
        res=(res*factorial_inv[n-r])%m;
        return res;
    }
    ll GCD(ll A,ll B){//GCD(A,B)
        while(A>=1 && B>=1){
            if(A>=B) A=(A%B);
            else B=(B%A);
        }
        if(A!=0) return A;
        return B;
    }
    ll modlog(ll a,ll b,ll m){//a^x=b(mod m)を満たす最小のx(ないなら-1)
        a%=m;b%=m;
        ll lo=-1,hi=m;
        while(hi-lo>1){
            ll mid=(lo+hi)/2;
            if(mid*mid>=m) hi=mid;
            else lo=mid;
        }
        ll sqrtM=hi;
        map<ll,ll>baby;
        ll amari=a;
        for(ll r=1;r<sqrtM;r++){
            if(!baby.count(amari)) baby[amari]=r;
            amari=(amari*a)%m;
        }
        ll A=power(modinv(a,m),sqrtM,m);
        amari=b;
        for(ll q=0;q<sqrtM;q++){
            if(amari==1 && q>=1) return q*sqrtM;
            else if(baby.count(amari)) return q*sqrtM+baby[amari];
            amari=(amari*A)%m;
        }
        return -1;
    }
};
MATH math;
int main(){
    cout.tie()->sync_with_stdio(0);
    cin.tie(0);
    int N;cin>>N;
    
    ll dp[N+1][5];
    for(int i=0;i<=N;i++){
        for(int j=0;j<5;j++){
            dp[i][j]=0;
        }
    }
    dp[0][0]=1;
    for(int i=1;i<=N;i++){
        for(int j=0;j<5;j++){
            dp[i][j]=(dp[i][j]+dp[i-1][j]*26)%mod;
        }
        dp[i][1]=(dp[i][1]+dp[i-1][0])%mod;
        dp[i][2]=(dp[i][2]+dp[i-1][1])%mod;
        dp[i][3]=(dp[i][3]+dp[i-1][2])%mod;
        dp[i][4]=(dp[i][4]+dp[i-1][3])%mod;
    }
    cout<<dp[N][4]<<endl;
}