N = int(input())
MOD = 998244353
dp = [[[0 for _ in range(3)] for _ in range(N//3+1)] for _ in range(N+1)]
dp[1][0][0] = 25
dp[1][0][1] = 1
for i in range(2,N+1):
    for j in range(N//3+1):
        dp[i][j][0] = (dp[i-1][j][0]*25)%MOD
        if j>=1:
            dp[i][j][0] = (dp[i][j][0]+dp[i-1][j-1][2])%MOD
        dp[i][j][1] = (dp[i-1][j][1]*25+dp[i-1][j][0])%MOD
        dp[i][j][2] = (dp[i-1][j][2]*25+dp[i-1][j][1])%MOD
ans = 0
for j in range(1,N//3+1):
    ans = (ans+(dp[N][j][0]+dp[N][j][1]+dp[N][j][2])*j)%MOD
print(ans)