#include<bits/stdc++.h>
using namespace std;

using ll = long long;

#define TYPE_OF( VAR ) remove_const<remove_reference<decltype( VAR )>::type >::type
#define CIN( LL , A ) LL A; cin >> A 
#define ASSERT( A , MIN , MAX ) assert( MIN <= A && A <= MAX ) 
#define CIN_ASSERT( A , MIN , MAX ) CIN( TYPE_OF( MAX ) , A ); ASSERT( A , MIN , MAX ) 
#define FOREQ( VAR , INITIAL , FINAL ) for( TYPE_OF( FINAL ) VAR = INITIAL ; VAR <= FINAL ; VAR ++ )  
#define QUIT return 0 
#define RETURN( ANSWER ) cout << ( ANSWER ) << "\n"; QUIT 

#define CHECK_REDUNDANT_INPUT string VARIABLE_FOR_CHECK_REDUNDANT_INPUT = ""; cin >> VARIABLE_FOR_CHECK_REDUNDANT_INPUT; assert( VARIABLE_FOR_CHECK_REDUNDANT_INPUT == "" ); assert( ! cin );

int main()
{
  constexpr const int bound_N = 3000;
  CIN_ASSERT( N , 3 , bound_N );
  CHECK_REDUNDANT_INPUT;
  constexpr const int bound_length = bound_N + 2;
  ll count[2][bound_length] = {};
  int i_prev = 0;
  int i_curr = 1;
  count[i_prev][1] = 1;
  N++;
  constexpr const ll P = 998244353;
  FOREQ( total_length_plus , 2 , N ){
    ll ( &count_prev )[bound_length] = count[i_prev];
    ll ( &count_curr )[bound_length] = count[i_curr];
    FOREQ( length_plus , 1 , total_length_plus ){
      count_curr[length_plus] = ( count_prev[length_plus] * 25 + count_prev[length_plus - 1] ) % P;
    }
    swap( i_prev , i_curr );
  }
  ll ( &count_last )[bound_length] = count[i_prev];
  ll answer = 0;
  while( --N > 0 ){
    answer += count_last[N+1] * ( N / 3 );
  }
  RETURN( answer % P );
}