#include<bits/stdc++.h>
using namespace std;
vector<int> decimal_to_binary(long long N){
    vector<int> result;
    while(N != 0){
        result.insert(result.begin(),N%2);
        N = N/2;
    }
    return result;
}

//a^n mod pの高速計算
//O(log p)
long long calc_modulo_p(long long a,long long n,long long p){
    a = a%p;
    n = n%(p-1);
    vector<int> binary = decimal_to_binary(n);
    long long x = a;
    long long result = 1;
    int N = binary.size();
    for(int i=0;i<N;i++){
        if(binary[N-1-i] == 1){
            result = (result * x)%p;
        }
        x = (x*x)%p;
    }
    return result;
}

int main(){
	long long N,K;
	cin >> N >> K;
	char s[N];
	scanf("%s",&s);
	long long good_day = 0;
	for(int i=0;i<N;i++){
		if(s[i] == 'N'){
			good_day++;
			if(i > 0){
				if(s[i-1] == 'C'){
					good_day--;
				}
			}
		}
	}
	good_day = good_day-K;
	if(good_day <= 0){
		cout << 0 << endl;
	} else {
		cout << calc_modulo_p(2,good_day,998244353) << endl;
	}
}