N = int(input())
MOD = 998244353
K = 26
dp = [0]*(N+1)
dp[0] = 1
for i in range(N):
    ndp = [0]*(N+1)
    for j in range(i+2):
        ndp[j] = dp[j]*(K-1) % MOD
        if j:
            ndp[j] += dp[j-1]
            ndp[j] %= MOD
    dp = ndp

ans = 0
for i in range(N+1):
    ans += dp[i]*(i//3) % MOD
    ans %= MOD
print(ans)