import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################

s = input()
z = 1
ans = 0
mod = 998244353

for i in s:
    if i == "M":
        z *= 3
        z %= mod
    else:
        ans += z
        ans %= mod

print(ans)