#include <cstdio>
#include <algorithm>
#include <set>
#include <vector>
#define limit 524288
#define maxlog 20
#define mod 998244353
#define maxn 100000

namespace cltstream
{
	#define size 1048576
	char cltin[size + 1], *ih = cltin, *it = cltin;
	inline char gc()
	{
		#ifdef ONLINE_JUDGE
		if (ih == it)
		{
			it = (ih = cltin) + fread(cltin, 1, size, stdin);
			if (ih == it)
				return EOF;
		}
		return *ih++;
		#else
		return getchar();
		#endif
	}

	char cltout[size + 1], *oh = cltout, *ot = cltout + size;
	inline void pc(char c)
	{
		if (oh == ot)
		{
			fwrite(cltout, 1, size, stdout);
			oh = cltout;
		}
		*oh++ = c;
	}
	#define clop() fwrite(cltstream::cltout, 1, cltstream::oh - cltstream::cltout, stdout), cltstream::oh = cltstream::cltout
	#undef size

	template <typename _tp>
	inline void read(_tp& x)
	{
		char c = gc();
		for (; c != 45 && (c < 48 || c > 57) && c != EOF; c = gc());
		int sgn = c == 45 ? c = gc(), -1 : 1;
		for (x = 0; c >= 48 && c <= 57 && c != EOF; x = (x << 3) + (x << 1) + (c ^ 48), c = gc());
		x *= sgn;
	}

	template <typename _tp>
	inline void write(_tp x, char text = -1)
	{
		if (x < 0)
			pc(45), x = -x;
		if (!x)
			pc(48);
		else
		{
			int digit[22];
			for (digit[0] = 0; x; digit[++digit[0]] = x % 10, x /= 10);
			for (; digit[0]; pc(digit[digit[0]--] ^ 48));
		}
		if (text >= 0)
			pc(text);
	}

	inline void put(char str[], char text = -1)
	{
		for (int cur = 0; str[cur]; pc(str[cur++]));
		if (text >= 0)
			pc(text);
	}
}

int unit[2][24];
int inv[limit], fac[limit], fav[limit];
int rev[limit];

inline int add(int a, int b) {
	return a + b < mod ? a + b : a + b - mod;
}

inline int sub(int a, int b) {
	return a - b >= 0 ? a - b : a - b + mod;
}

inline int pow(int a, int n) {
	int res = 1;
	for (; n; n >>= 1, a = 1LL * a * a % mod)
		if (n & 1)
			res = 1LL * res * a % mod;
	return res;
}

inline int C(int n, int m) {
	if (m >= 0 && m <= n)
		return 1LL * fac[n] * fav[m] % mod * fav[n - m] % mod;
	else
		return 0;
}

inline void InitIntUnit() {
	unit[0][23] = pow(3, 119);
	unit[1][23] = pow(332748118, 119);
	for(int i = 0; i < 2; ++i)
		for(int j = 22; j >= 0; --j)
			unit[i][j] = 1LL * unit[i][j + 1] * unit[i][j + 1] % mod;
}

inline void InitFac() {
	inv[1] = 1;
	for (int i = 2; i < limit; ++i)
		inv[i] = sub(0, 1LL * (mod / i) * inv[mod % i] % mod);
	fac[0] = fav[0] = 1;
	for (int i = 1; i < limit; ++i) {
		fac[i] = 1LL * fac[i - 1] * i % mod;
		fav[i] = 1LL * fav[i - 1] * inv[i] % mod;
	}
}

inline void Derivative(int F[], int n, int G[]) {
	for (int i = 0; i < n; ++i)
		G[i] = 1LL * (i + 1) * F[i + 1] % mod;
	G[n] = 0;
}

inline void Integration(int F[], int n, int G[], int C) {
	for (int i = n + 1; i > 0; --i)
		G[i] = 1LL * inv[i] * F[i - 1] % mod;
	G[0] = C;
}

inline void NTT(int F[], int N, int tp, int A[]) {
	for (int i = 0; i < N; ++i)
		A[i] = F[rev[i] = (rev[i >> 1] >> 1) | ((i & 1) ? (N >> 1) : 0)];
	for (int k = 1, p = 1; p < N; ++k, p <<= 1)
		for (int i = 0; i < N; i += p << 1)
			for (int j = i, tmp = 1; j < i + p; ++j, tmp = 1LL * tmp * unit[tp][k] % mod) {
				int x = A[j], y = 1LL * A[j + p] * tmp % mod;
				A[j] = add(x, y);
				A[j + p] = sub(x, y);
			}
	if (tp == 1) {
		int v = pow(N, mod - 2);
		for (int i = 0; i < N; ++i)
			A[i] = 1LL * A[i] * v % mod;
	}
}

inline void Prod(int F[], int n, int G[], int m, int H[]) {
	static int A[limit], B[limit], C[limit];
	int N = 1;
	for (; N < n + m + 1; N <<= 1);
	for (int i = n + 1; i < N; ++i)
		F[i] = 0;
	for (int i = m + 1; i < N; ++i)
		G[i] = 0;
	NTT(F, N, 0, A);
	NTT(G, N, 0, B);
	for (int i = 0; i < N; ++i)
		C[i] = 1LL * A[i] * B[i] % mod;
	NTT(C, N, 1, H);
	for (int i = n + m + 1; i < N; ++i)
		H[i] = 0;
}

inline void Inv(int F[], int n, int G[]) {
	static int tmp[limit], res[limit];
	res[0] = pow(F[0], mod - 2);
	for (int i = 1; i - 1 < n; i <<= 1) {
		for (int j = 0; j < 2 * i; ++j)
			tmp[j] = F[j];
		Prod(tmp, 2 * i - 1, res, i - 1, tmp);
		for (int j = 0; j < 2 * i; ++j)
			tmp[j] = sub(0, tmp[j]);
		tmp[0] = add(tmp[0], 2);
		Prod(tmp, 2 * i - 1, res, i - 1, res);
	}
	for (int i = 0; i <= n; ++i)
		G[i] = res[i];
}

int n, m;
int a[maxn + 5];
char s[maxn + 5];
int cnt[maxn + 5];
int f[limit], g[limit], h[limit];
int pos[limit], neg[limit], invneg[limit], ans[limit];

void dfs(int arr[], int cur, int l, int r) {
	if (l < r) {
		int mid = (l + r) >> 1;
		dfs(arr, cur << 1, l, mid);
		dfs(arr, cur << 1 | 1, mid + 1, r);
		f[0] = 1;
		for (int i = l; i <= mid; ++i)
			f[i - l + 1] = arr[i];
		g[0] = 1;
		for (int i = mid + 1; i <= r; ++i)
			g[i - mid] = arr[i];
		Prod(f, mid - l + 1, g, r - mid, h);
		for (int i = l; i <= r; ++i)
			arr[i] = h[i - l + 1];
	}
}

int main()
{
	InitIntUnit();
	InitFac();

	cltstream::read(n);
	cltstream::read(m);
	for (int i = 1; i <= n; ++i)
		cltstream::read(a[i]);
	for (int i = 1; i <= m; ++i)
		for (; s[i] != 'a' && s[i] != 's'; s[i] = cltstream::gc());
	for (int i = m, j = 0; i >= 0; j += (s[i] == 's'), --i) {
		++cnt[j];
		--cnt[j + 1];
	}
	int poslen = 0;
	for (int i = 0; i <= m + 1; ++i)
		for (int j = 1; j <= cnt[i]; ++j)
			pos[++poslen] = sub(0, i);
	dfs(pos, 1, 1, poslen);
	pos[0] = 1;
	int neglen = 0;
	for (int i = 0; i <= m + 1; ++i)
		for (int j = 1; j <= -cnt[i]; ++j)
			neg[++neglen] = sub(0, i);
	dfs(neg, 1, 1, neglen);
	neg[0] = 1;
	Inv(neg, n, invneg);
	Prod(pos, poslen, invneg, n, ans);
	int sum = 0;
	for (int i = 1; i <= n; ++i)
		sum = add(sum, 1LL * ans[i - 1] * ans[n - i] % mod * a[i] % mod);
	cltstream::write(sum);
	clop();
	return 0;
}