#include <iostream>
#include <string>
#include <bitset>
#include <vector>
using namespace  std;
int main(){
  int Kr,Kb; string S;
  cin>>Kr>>Kb;
  cin>>S;
  vector<int> v1;
  for(int i=0;i<S.size();++i){
    if(S[i]=='B' || S[i]=='R') v1.push_back(i);
  }
  int ans=0;
  for(int i=0;i<1048576;++i){
    bitset<20> bs1(i);
    string S2=S;
    int a=0;
    for(int j=0;j<20;++j){
      if(!bs1.test(j)){
        S2.erase(v1[j]-a,1);
        a+=1;
      }
    }
    bool check=true;
    for(int j=0;j<S2.size();++j){
      if(S2[j]=='R' && j+Kr<S2.size() && S2[j+Kr]=='R'){
        check=false;break;
      }
      if(S2[j]=='R' && j-Kr>=0 && S2[j-Kr]=='R'){
        check=false;break;
      }
      if(S2[j]=='B' && j+Kb<S2.size() && S2[j+Kb]=='B'){
        check=false;break;
      }
      if(S2[j]=='B' && j-Kb>=0 && S2[j-Kb]=='B'){
        check=false;break;
      }
    }
    if(check && ans<S2.size()) ans=S2.size();
  }
  cout<<ans<<endl;
}