#include <algorithm>
#include <bit>
#include <iostream>
#include <string>
constexpr int N = 1 << 19;
namespace poly
{
	constexpr int mod = 998244353, g = 3;
	int mul(int a, int b) { return static_cast<long long>(a) * b % mod; }
	int pow(int b, int e) { int r = 1; while (e) { if (e & 1) r = mul(r, b); e >>= 1, b = mul(b, b); } return r; }
	void reduce(int& a) { a += a >> 31 & mod; }
	int n;
	int rev[N];
	int p[N >> 1];
	int inv_n;
	void init(int n_)
	{
		n = std::bit_ceil(static_cast<unsigned>(n_)), n_ = n >> 1;
		for (int i = 0; i < n; i += 2)
			rev[i] = rev[i >> 1] >> 1, rev[i + 1] = rev[i] | n_;
		int p1 = pow(g, (mod - 1) / n); p[0] = 1;
		for (int i = 1; i < n_; ++i)
			p[i] = mul(p[i - 1], p1);
		inv_n = pow(n, mod - 2);
	}
	void NTT(int *a)
	{
		for (int i = 0; i < n; ++i)
			if (i < rev[i]) std::swap(a[i], a[rev[i]]);
		for (int i = 1; i < n; i <<= 1)
			for (int j = 0; j < n; j += i << 1)
				for (int k = 0; k < i; ++k)
				{
					int& u = a[j + k], & v = a[j + i + k];
					int t_f = mul(p[k * ((n >> 1) / i)], v);
					reduce(v = u - t_f), reduce(u += t_f - mod);
				}
	}
	void mul(int *a, int *b, int *c)
	{
		NTT(a), NTT(b);
		for (int i = 0; i < n; ++i)
			c[i] = mul(a[i], b[i]);
		NTT(c);
		std::reverse(c + 1, c + n);
		for (int i = 0; i < n; ++i)
			c[i] = mul(c[i], inv_n);
	}
}
int a[N], b[N], co[N], ck[N];
int cnt_o[N], cnt_k[N];
int cnt[N];
int f[N];
int main()
{
	int o, k; std::cin >> o >> k;
	std::string S; std::cin >> S; int m = S.size();
	for (int i = 0; i < m; ++i)
		cnt_o[i + 1] = cnt_o[i] + (S[i] == 'o');
	for (int i = 0; i < m; ++i)
		cnt_k[i + 1] = cnt_k[i] + (S[i] == 'k');
	std::string P; std::cin >> P; int n = P.size();
	for (int i = 0; i < m; ++i)
		a[i] = S[m - 1 - i] == 'o';
	for (int i = 0; i < n; ++i)
		b[i] = P[i] == 'k';
	poly::init(m + n - 1);
	poly::mul(a, b, co);
	std::fill_n(a, poly::n, 0);
	for (int i = 0; i < m; ++i)
		a[i] = S[m - 1 - i] == 'k';
	std::fill_n(b, poly::n, 0);
	for (int i = 0; i < n; ++i)
		b[i] = P[i] == 'o';
	poly::mul(a, b, ck);
	int j = m;
	for (int i = n; i <= m; ++i)
	{
		--j;
		cnt[i] = co[j] + ck[j];
	}
	for (int i = n; i <= m; ++i)
		f[i] = std::max(f[i - 1], f[i - n] + (cnt[i] <= 30 ? o * (cnt_o[i] - cnt_o[i - n]) + k * (cnt_k[i] - cnt_k[i - n]) >> cnt[i] : 0));
	std::cout << f[m] << "\n";
}