n = int(input())
mod = 998244353
dp = [[0] * (n+1) for i in range(n+1)]
dp[0][0] = 1
for i in range(n):
  for j in range(n):
    dp[i+1][j] += dp[i][j] * 25
    dp[i+1][j+1] += dp[i][j]
    dp[i+1][j] %= mod
ans = 0
# print(*dp, sep = "\n")
for i in range(3, n+1, 3):
  ans += sum(dp[n][i:min(n+1, i+3)]) * (i // 3)
  ans %= mod
print(ans)