N = int(input())

P = 998244353
ans = 0

inf = 1000
dp = [[0] * (inf + 1) for _ in range(3)]
dp[0][0] = 1
for _ in range(N):
    nx = [[0] * (inf + 1) for _ in range(3)]
    for i in range(inf + 1):
        nx[0][i] += dp[0][i] * 25
        nx[1][i] += dp[1][i] * 25 + dp[0][i]
        nx[2][i] += dp[2][i] * 25 + dp[1][i]
        if i < inf:
            nx[0][i + 1] += dp[2][i]
    for i in range(inf + 1):
        for j in range(3):
            nx[j][i] %= P
    dp = nx
ans = 0
for i in range(inf + 1):
    for j in range(3):
        ans += dp[j][i] * i
        ans %= P
print(ans)