n = int(input())
mod = 998244353
ma = (n//3+1)*3
dp = [0]*(ma+1)
dp[0] = 1

for i in range(n):
    for j in range(ma+1)[::-1]:
        if dp[j] == 0:
            continue
        dp[j+1] += dp[j]
        dp[j+1] %= mod
        dp[j] *= 25
        dp[j] %= mod

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