mod = 998244353
n = int(input())
S = [ord(s)-ord("a") for s in input()]
dp = [[0]*2 for _ in range(2)]
dp[0][0] = 1
for s in S:
    ndp = [[0]*2 for _ in range(2)]
    for j0 in range(2):
        for k0 in range(2):
            for j1 in range(2):
                for k1 in range(2):
                    if j0 > j1 or k0 > k1:
                        continue
                    if k0 < k1:
                        if not (j0 or (j1 ^ (s == 0))):
                            continue
                        c = 1
                    else:
                        if (j0,j1) == (0,0):
                            c = s > 0
                        elif (j0,j1) == (0,1):
                            c = max(s-1,0)
                        else:
                            c = 25
                    ndp[j1][k1] += dp[j0][k0]*c
                    ndp[j1][k1] %= mod
    dp = ndp
print(dp[1][1])