import itertools as iter
import collections as coll
import heapq as hq
import bisect as bis
from decimal import Decimal as dec
from copy import deepcopy as dcopy
import math
import sys
sys.setrecursionlimit(10**6)
def input():
    return sys.stdin.readline().rstrip()
def getN():
	return int(sys.stdin.readline())
def getNs():
	return map(int,sys.stdin.readline().split())
def getList():
	return list(map(int,sys.stdin.readline().split()))
def strinps(n):
	return [sys.stdin.readline().rstrip() for _ in range(n)]
pi = 3.141592653589793
mod = 10**9+7
MOD = 998244353
INF = math.inf
dx = [1,0,-1,0];	dy = [0,1,0,-1]

def ctoi(char):
	return ord(char)-ord('a')

"""
Main Code
"""

n = getN()
s = input()
l = [ctoi(c) for c in s]

dp = [[0]*4 for _ in [0]*n]
ndp = dcopy(dp)
dp[0][0b00] = max(0,l[0]-1)
dp[0][0b01] = int(l[0] != 0)
dp[0][0b10] = int(l[0] != 0)
dp[0][0b11] = int(l[0] == 0)
#print(dp)
for i in range(1,n):
	# 0 を 1 つも含まず、S より小さい
	dp[i][0b00] += dp[i-1][0b00] * 25;				dp[i][0b00] %= MOD
	dp[i][0b00] += dp[i-1][0b10] * max(0,l[i]-1);	dp[i][0b00] %= MOD
	# 0 を 1 つだけ含み、S より小さい
	dp[i][0b01] += dp[i-1][0b00];					dp[i][0b01] %= MOD
	dp[i][0b01] += dp[i-1][0b01] * 25;				dp[i][0b01] %= MOD
	dp[i][0b01] += dp[i-1][0b10] * (l[i] != 0);		dp[i][0b01] %= MOD
	dp[i][0b01] += dp[i-1][0b11] * max(0,l[i]-1);	dp[i][0b01] %= MOD
	# 0 を 1 つも含まず、S と等しい
	dp[i][0b10] += dp[i-1][0b10] * (l[i] != 0);		dp[i][0b10] %= MOD
	# 0 を 1 つだけ含み、S と等しい
	dp[i][0b11] += dp[i-1][0b10] * (l[i] == 0);		dp[i][0b11] %= MOD
	dp[i][0b11] += dp[i-1][0b11] * (l[i] != 0);		dp[i][0b10] %= MOD
	#print(dp)
print(dp[n-1][0b01])