#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long int ll;
typedef long double ld;
#define FOR(i,l,r) for(ll i=l;i<r;i++)
#define REP(i,n) FOR(i,0,n)
#define RFOR(i,l,r) for(ll i=r-1;i>=l;i--)
#define RREP(i,n) RFOR(i,0,n)
#define ALL(x) x.begin(),x.end()
#define P pair<ll,ll>
#define F first
#define S second
#define BS(A,x) binary_search(ALL(A),x)
#define LB(A,x) (ll)(lower_bound(ALL(A),x)-A.begin())
#define UB(A,x) (ll)(upper_bound(ALL(A),x)-A.begin())
#define COU(A,x) UB(A,x)-LB(A,x)
template<typename T>using min_priority_queue=priority_queue<T,vector<T>,greater<T>>;
using mint=modint1000000007;
signed main(){
  ll Kr,Kb,ans=10;string S;cin>>Kr>>Kb>>S;vector<ll>R,B;
  REP(i,S.size()){if(S[i]=='R')R.push_back(i);if(S[i]=='B')B.push_back(i);}
  REP(r,1024)REP(b,1024){
    REP(i,30)S[i]='W';
    REP(i,10){if((r>>i)&1)S[R[i]]='R';else S[R[i]]='O';}
    REP(i,10){if((b>>i)&1)S[B[i]]='B';else S[B[i]]='O';}
    string T;REP(i,30)if(S[i]!='O')T+=S[i];REP(i,30)T+='O';bool x=1;
    REP(i,T.size()){
      if(T[i]=='R'&&T[i+Kr]=='R')x=0;
      if(T[i]=='B'&&T[i+Kb]=='B')x=0;
    }
    if(x)ans=max(ans,(ll)T.size()-30);
  }
  cout<<ans<<endl;
  return 0;
}