#include<bits/stdc++.h>
#include<atcoder/modint>
using namespace std;

int main(){
	using mint=atcoder::modint998244353;
	string s;
	cin>>s;
	int n=s.size();
	mint sum=0;
	mint ans=0;
	vector<int> cnt(n+1);
	for (int i=n-1;i>=0;i--) cnt[i]=cnt[i+1]+(s[i]=='A');
	for (int i=0;i<n;i++){
		if (s[i]=='M'){
			ans+=(sum+1)*2*cnt[i];
			sum+=(sum+1)*2;
		}
	}
	ans+=cnt[0];
	cout<<ans.val()<<endl;
}