def accum_dp(xs: list, f, op, e, init: dict):
    dp = init.copy()
    for x in xs:
        pp = {}
        dp, pp = pp, dp
        for fm_key, fm_val in pp.items():
            for to_key, to_val in f(fm_key, fm_val, x):
                dp[to_key] = op(dp.get(to_key, e), to_val)

    return dp


def op(a, b):
    return (a + b) % MOD


def f(k, v, x):
    match k:
        case 'S':
            yield 'm', v
            yield k, v * 26

        case 'm':
            yield 'o', v
            yield k, v * 26

        case 'o':
            yield 'l', v
            yield k, v * 26

        case 'l':
            yield 'e', v
            yield 'G', v
            yield k, v * 26

        case 'e':
            # yield 'G', v
            yield k, v * 26

        case 'G':
            yield k, v * 26



MOD = 998244353
N = int(input())

init = {'S': 1}
dp = accum_dp(list(range(N)), f, op, 0, init)
ans = dp.get('G', 0) % MOD
print(ans)