#include<iostream>
#include<vector>
#include<algorithm>

using namespace std;
using ll = long long;

#include<set>
int main(){
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int a,b;
    cin>>a>>b;
    set<pair<string,int>> memo;
    int ans = 0;
    
    auto dfs = [&](auto dfs,string s,int ni) -> void {
        if(memo.count(make_pair(s,ni))) return;
        memo.insert(make_pair(s,ni));
        bool fn = true;
        for(int i = 0;i<s.size();i++){
            if(i+a<s.size()&&s[i]=='R'&&s[i+a]=='R') fn = false;
            if(i+b<s.size()&&s[i]=='B'&&s[i+b]=='B') fn = false;
            if(!fn) break;
        }

        if(fn){
        
            ans = max<int>(ans,s.size());
            return;
        }
        if(ni+1<s.size()) dfs(dfs,s,ni+1);
        if(s[ni]=='W') return;
        string t;
        for(int i = 0;i<s.size();i++) if(i!=ni) t += s[i];
        dfs(dfs,t,ni);
    };
    string s;
    cin>>s;
    dfs(dfs,s,0);
    cout<<ans<<endl;

}