n = int(input()); mod = 998244353
dp = [1]+[0]*n; ans = 0
for _ in range(n):
    for j in range(n, -1, -1):
        dp[j] = dp[j]*25%mod
        if j: dp[j] = (dp[j]+dp[j-1])%mod
for i, v in enumerate(dp): ans = (ans+i//3*v)%mod
print(ans)