MOD = 998244353

N = int(input())
A = input().strip()

ans = 1
i = 0

while i < N:
    j = i
    while j + 1 < N and A[j] != A[j+1]:
        j += 1

    length = j - i + 1
    ans = ans * (length + 1) % MOD

    i = j + 1

print(ans)