#include <cmath>
#include <cstdio>
#include <cctype>
#include <cstring>
#include <complex>
#include <algorithm>
inline int getint() {
	char ch;
	while(!isdigit(ch=getchar()));
	int x=ch^'0';
	while(isdigit(ch=getchar())) x=(((x<<2)+x)<<1)+(ch^'0');
	return x;
}
#define int long long
using ll=long long;
using int64=long long;
constexpr int N=250002*10;
constexpr int MOD=998244353;
char s[N],p[N];
int sum[N],f[N];
ll so[N],sk[N],po[N],pk[N],r[N];
int lim,L,n,m;
ll power (ll x,ll k){ll res=1;while (k){if (k&1) res=res*x%MOD;x=x*x%MOD,k>>=1;}return res;}
const ll G=3,Gi=power (G,MOD-2),inv2=power (2,MOD-2);
void init (int len)
{
	lim=1,L=0;
	while (lim<len) lim<<=1,L++;
	for (int i=0;i<lim;i++) r[i]=(r[i>>1]>>1)|((i&1)<<(L-1));
}
void NTT (ll *a,int opt)
{
	for (int i=0;i<lim;i++) if (i<r[i]) std::swap (a[i],a[r[i]]);
	for (int mid=1;mid<lim;mid<<=1)
	{
		ll Wn=power (opt==1?G:Gi,(MOD-1)/(mid<<1));
		for (int R=mid<<1,j=0;j<lim;j+=R)
		{
			ll W=1;
			for (int k=0;k<mid;k++,W=W*Wn%MOD)
			{
				ll x=a[j+k],y=W*a[j+mid+k]%MOD;
				a[j+k]=(x+y)%MOD,a[j+mid+k]=(x-y+MOD)%MOD;
			}
		}
	}
	if (opt==-1){ll inv=power (lim,MOD-2);for (int i=0;i<lim;i++) a[i]=a[i]*inv%MOD;}
}
void mul (ll *a,int n,ll *b,int m)
{
	init (n+m),NTT (a,1),NTT (b,1);
	for (int i=0;i<lim;i++) a[i]=a[i]*b[i]%MOD;
	NTT (a,-1),NTT (b,-1);
}
int diff(const int &l) {
	return so[l]+sk[l];
}
signed main() {
	const int o=getint(),k=getint();
	scanf("%s",&s[1]);
	scanf("%s",&p[1]);
	n=strlen(&s[1]),m=strlen(&p[1]);
	for(int i=1;i<=n;i++) {
		sum[i]=sum[i-1]+(s[i]=='o'?o:k);
		so[i]=s[i]=='o';
		sk[i]=s[i]=='k';
	}
	for(int i=1;i<=m;i++) {
		po[m-i]=p[i]=='o';
		pk[m-i]=p[i]=='k';
	}
	mul(&so[1],n,pk,m);
	mul(&sk[1],n,po,m);
	/*for(int i=1;i<=n*2;i++) {
		printf("%lld%c",so[i]," \n"[i==n*2]);
	}
	for(int i=1;i<=n*2;i++) {
		printf("%lld%c",sk[i]," \n"[i==n*2]);
	}*/
	for(int i=m;i<=n;i++) {
		f[i]=std::max(f[i-1],f[i-m]+((sum[i]-sum[i-m])>>std::min(diff(i),32ll)));
		//printf("````%d %d %d\n",i-m+1,i,diff(i-m+1));
	}
	printf("%lld\n",f[n]);
}