#include <bits/stdc++.h>
#include <atcoder/modint>
using namespace std;
using ll = long long;
using mint = atcoder::modint998244353;
const ll INF = LLONG_MAX / 4;
#define rep(i,a,b) for(ll i = a; i < b; i++)
template<class T, class U> bool chmax(T& a, U b){ if(a >= b) return 0; a = b; return 1; }


int main(){
    ll N;
    cin >> N;
    mint ans = 0;
    auto binom = [&](ll n, ll r){
        static auto fac = [&]{
            vector<mint> fac = {1};
            for(ll i = 1; i <= N; i++) fac.push_back(fac.back() * i);
            return fac;
        }();
        static auto inv = [&]{
            vector<mint> inv(N + 1);
            for(ll i = 0; i <= N; i++) inv[i] = fac[i].inv();
            return inv;
        }();
        return fac[n] * inv[r] * inv[n - r];
    };
    for(ll n = 3; n <= N; n += 3){
        for(ll m = 0; m + n <= N; m++){
            ans += mint{26}.pow(m) * mint{25}.pow(N - n - m) * binom(N - m - 1, n - 1);
        }
    }
    cout << ans.val() << endl;
}