N = int(input())

mod = 998244353

dp = [[[0]*3 for _ in range(N//3+1)] for _ in range(N+1)]
dp[0][0][0] = 1
for i in range(1,N+1):
    for j in range(N//3+1):
        dp[i][j][0] += dp[i-1][j][0]*25
        dp[i][j][0] %= mod
        dp[i][j][1] += (dp[i-1][j][0]+dp[i-1][j][1]*25)
        dp[i][j][1] %= mod
        dp[i][j][2] += (dp[i-1][j][1]+dp[i-1][j][2]*25)
        dp[i][j][2] %= mod
        if j+1<=N//3:
            dp[i][j+1][0] += dp[i-1][j][2]
            dp[i][j+1][0] %= mod
res = 0
for j in range(1,N//3+1):
    res += j*sum(dp[-1][j])
    res %= mod
print(res)