from collections import *
from itertools import *
from functools import *
from heapq import *
import sys,math
input = sys.stdin.readline

N = int(input())
mod = 998244353
# class combination():
    
#     def __init__(self,N,p):
        
        
#         self.fact = [1, 1]  # fact[n] = (n! mod p)
#         self.factinv = [1, 1]  # factinv[n] = ((n!)^(-1) mod p)
#         self.inv = [0, 1]  # factinv 計算用
#         self.p = p
        
#         for i in range(2, N + 1):
#             self.fact.append((self.fact[-1] * i) % p)
#             self.inv.append((-self.inv[p % i] * (p // i)) % p)
#             self.factinv.append((self.factinv[-1] * self.inv[-1]) % p)
        

#     def cmb(self,n, r):
#         if (r < 0) or (n < r):
#             return 0
#         r = min(r, n - r)
#         return self.fact[n] * self.factinv[r] * self.factinv[n-r] % self.p
        
# C = combination(10000)

M = N//3 + 1

dp = [[[0]*N for j in range(M+1)] for _ in range(3)]
dp[0][0][0] = 1

for i in range(N-1):
    
    
    for j in range(M):
        
        for k in range(3):
            
            #dp[k][j][i] 
            if k==2:
                dp[0][j+1][i+1] = (dp[0][j+1][i+1] + dp[k][j][i])%mod
            else:
                dp[k+1][j][i+1] = (dp[k+1][j][i+1] + dp[k][j][i])%mod
            
            dp[k][j][i+1] = (dp[k][j][i+1] + 25*dp[k][j][i])%mod
            if (k==0)&(j==0):
                dp[k][j][i+1] = (dp[k][j][i+1] + pow(25,i+1,mod))%mod
            
ans = 0
for j in range(M+1):
    
    ans += dp[2][j][-1]*(j+1)
    ans += dp[1][j][-1]*(j)
    ans += dp[0][j][-1]*(j)
    ans %= mod

# print(dp[2])
# print(dp)
print(ans)