#include "bits/stdc++.h"
#define rep(i, a, n) for (auto i = a; i <= (n); ++i)
#define revrep(i, a, n) for (auto i = n; i >= (a); --i)
#define all(a) a.begin(), a.end()
#define sz(a) (int)(a).size()
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

template<const int &mod> struct Z {
	int x;
	Z(ll a = 0): x(a % mod) { if (x < 0) x += mod; }
	explicit operator int() const { return x; }

	Z& operator +=(Z b) { x += b.x; if (x >= mod) x -= mod; return *this; }
	Z& operator -=(Z b) { x -= b.x; if (x < 0) x += mod; return *this; }
	Z& operator *=(Z b) { x = 1ll * x * b.x % mod; return *this; }
	friend Z operator +(Z a, Z b) { return a += b; }
	friend Z operator -(Z a, Z b) { return a -= b; }
	friend Z operator *(Z a, Z b) { return a *= b; }

	Z pow(ll k) const {
		Z res = 1, a = *this;
		for (; k; k >>= 1, a = a * a) if (k & 1) res = res * a;
		return res;
	}
	Z& operator /=(Z b) {
		assert(b.x != 0);
		*this = *this * b.pow(mod - 2);
		return *this;
	}
	friend Z operator /(Z a, Z b) { return a/= b; }
};
const int mod = 998244353;
using Mint = Z<mod>;

int main() {
	ios::sync_with_stdio(0); cin.tie(0);

	int n, k; cin >> n >> k;
	string s; cin >> s;
	auto cal = [&](const string &t) {
		vector<Mint> dp(n + 1);
		dp[0] = 1;
		for (auto c: t) {
			rep(i, 0, n - 1) dp[i + 1] += dp[i];
			vector<Mint> ndp(n + 1);
			rep(i, 0, n - 1) if (s[i] == c) {
				ndp[i] += dp[i];
			}
			swap(dp, ndp);
		}
		return accumulate(dp.begin(), dp.begin() + n, Mint{0});
	};
	auto binom = [&](Mint n, int m) -> Mint {
		Mint ans = 1;
		rep(i, 0, m - 1) ans *= n - i;
		rep(i, 1, m) ans /= i;
		return ans;
	};
	Mint ans = 0;
	ans += cal("WAC") * binom(k, 1);
	ans += cal("WA") * cal("C") * binom(k, 2);
	ans += cal("W") * cal("AC") * binom(k, 2);
	ans += cal("W") * cal("A") * cal("C") * binom(k, 3);
	printf("%d\n", (int) ans);
	return 0;
}