#include <iostream>
#include <cstdio>
#include <cstring>
#define p 998244353
#define nn 250005
#define mn 533333

using namespace std;

int o, k, n, m, s0[nn], s1[nn], s2[nn], dp[nn];
char s[nn], t[nn];

int Pow(int a, int b) {
	int ans = 1;
	for(; b; b & 1 ? ans = 1ll * ans * a % p : 0, a = 1ll * a * a % p, b >>= 1);
	return ans;
}


int N, l, f0[mn], f1[mn], g0[mn], g1[mn], r[mn];
void pre(int maxp) {
	N = 1, l = -1;
	while(N <= maxp) N <<= 1, ++l;
	for(int i = 0; i < N; ++i) {
		r[i] = r[i >> 1] >> 1 | (i & 1) << l;
	}
}
int mod(int x) { return x >= p ? x - p : x; }
void NTT(int *a, int rev) {
	for(int i = 0; i < N; ++i) if(i < r[i]) {
		swap(a[i], a[r[i]]);
	}
	for(int h = 1; h < N; h <<= 1) {
		int n = h << 1, wn = Pow(3, (p - 1) / n);
		if(rev) wn = Pow(wn, p - 2);
		for(int j = 0; j < N; j += n) {
			for(int k = 0, w = 1; k < h; ++k, w = 1ll * w * wn % p) {
				int x = a[j + k], y = 1ll * w * a[j + h + k] % p;
				a[j + k] = mod(x + y), a[j + h + k] = mod(x - y + p);
			}
		}
	}
	if(rev) {
		int inv = Pow(N, p - 2);
		for(int i = 0; i < N; ++i) {
			a[i] = 1ll * a[i] * inv % p;
		}
	}
}

int calc(int i) {
	int v = o * (s0[i] - s0[i - m]) + k * (s1[i] - s1[i - m]);
	int g = m - f0[i] - f1[i] - s2[m];
	while(v > 0 && g > 0) {
		v >>= 1, --g;
	}
	// printf("%d %d\n", i, v);
	return v;
}

int main() {
	scanf("%d%d", &o, &k);
	scanf("%s", s + 1), scanf("%s", t + 1);
	n = strlen(s + 1), m = strlen(t + 1);
	for(int i = 1; i <= n; ++i) {
		s0[i] = s0[i - 1], s1[i] = s1[i - 1];
		if(s[i] == 'o') {
			f0[i] = 1, ++s0[i];
		}
		else {
			f1[i] = 1, ++s1[i];
		}
	}
	for(int i = 1; i <= m; ++i) {
		s2[i] = s2[i - 1];
		if(t[i] == 'o') {
			g0[m - i] = 1;
		}
		else if(t[i] == 'k') {
			g1[m - i] = 1;
		}
		else {
			++s2[i];
		}
	}
	pre(n + m - 1);
	NTT(f0, 0), NTT(g0, 0);
	for(int i = 0; i < N; ++i) {
		f0[i] = 1ll * f0[i] * g0[i] % p;
	}
	NTT(f0, 1);
	NTT(f1, 0), NTT(g1, 0);
	for(int i = 0; i < N; ++i) {
		f1[i] = 1ll * f1[i] * g1[i] % p;
	}
	NTT(f1, 1);

	// for(int i = 1; i <= n; ++i) {
	// 	printf("%d %d\n", f0[i], f1[i]);
	// }

	dp[0] = 0;
	for(int i = 1; i <= n; ++i) {
		dp[i] = dp[i - 1];
		if(i >= m) {
			dp[i] = max(dp[i], dp[i - m] + calc(i));
		}
	}
	printf("%d", dp[n]);
	return 0;
}