n = int(input())
ans = 0
mod = 998244353

def cmb(n, r, mod):
    if ( r<0 or r>n ):
        return 0
    r = min(r, n-r)
    return g1[n] * g2[r] * g2[n-r] % mod
 #出力の制限
N = 10000
g1 = [1, 1] # 元テーブル
g2 = [1, 1] #逆元テーブル
inverse = [0, 1] #逆元テーブル計算用テーブル

for i in range( 2, N + 1 ):
    g1.append( ( g1[-1] * i ) % mod )
    inverse.append( ( -inverse[mod % i] * (mod//i) ) % mod )
    g2.append( (g2[-1] * inverse[-1]) % mod )

for i in range(1,n):
    if n >= i * 3:
        for j in range(3*i,n+1):
            C = cmb(j-1,3*i-1,mod)
            ans += C * pow(25,j-1-(3*i-1),mod) * pow(26,n-(j),mod)
print(ans%mod)