#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 1010
#define fs first
#define sc second
#define ii pair<int,int>
#define iii pair<ii,int>
#define ld long double
#define pb push_back
#define int ll
const ll mod=1e9+7;
int mu2[N],n,k,a[N];
vector<int>l,r,dq;
ii dp[N][N][2];
void selfadd(int&u,int v)
{
u=(u+v)%mod;
}
ii get(int pos,int k,int id,int dabe)
{
if(pos==0)
return{0,(k==0)};
if(dabe&&dp[pos][k][id].fs!=-1)
return dp[pos][k][id];
ii res={0,0};
// cout<<pos<<" "<<k<<" "<<id<<endl;
//ko doi
int i=(id^a[pos]);
if(dabe||i<=dq[pos-1])
{
ii cc=get(pos-1,k,id,(dabe|(i<dq[pos-1])));
selfadd(res.fs,cc.fs+cc.sc*mu2[pos-1]*i);
selfadd(res.sc,cc.sc);
}
if(k>0)
{
i=((id^a[pos])^1);
if(dabe||i<=dq[pos-1])
{
ii cc=get(pos-1,k-1,(id^1),(dabe|(i<dq[pos-1])));
selfadd(res.fs,cc.fs+cc.sc*mu2[pos-1]*i);
selfadd(res.sc,cc.sc);
}
}
if(dabe)
dp[pos][k][id]=res;
return res;
}
int solve(vector<int>s)
{
//for(int i=n-1;i>=0;i--)cout<<s[i]<<" ";
if(s[n-1]==0)
return 0;
dq=s;
ii A=get(n-1,k,0,0),B=get(n-1,k,1,0);
selfadd(A.fs,B.fs);
selfadd(A.sc,B.sc);
return(A.fs+A.sc*mu2[n-1])%mod;
}
int32_t main()
{
// freopen("A.inp","r",stdin);
// freopen("A.out","w",stdout);
cin.tie(NULL);
cout.tie(NULL);
ios::sync_with_stdio(0);
cin>>n>>k;
for(int i=n-1;i>=1;i--)
{
char ch;
cin>>ch;
a[i]=(ch=='R');
}
mu2[0]=1;
for(int i=1;i<=n;i++)
mu2[i]=mu2[i-1]*2%mod;
l.resize(n+1,0);
r.resize(n+1,0);
for(int i=n-1;i>=0;i--)
{
char ch;
cin>>ch;
l[i]=ch-'0';
// cin>>l[i];
}
for(int i=n-1;i>=0;i--)
{
char ch;
cin>>ch;
r[i]=ch-'0';
}
for(int i=0;i<=1005;i++)
for(int j=0;j<=1005;j++)
dp[i][j][0]=dp[i][j][1]={-1,-1};
int res=solve(r);
for(int i=0;i<=n-1;i++)
if(l[i]==1)
{
l[i]=0;
for(int j=0;j<i;j++)
l[j]=1;
break;
}
cout<<(res-solve(l)+mod*mod)%mod;
return 0;
}
