#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

int main(){
    int kr, kb; cin >> kr >> kb;
    string s;
    cin >> s;
    int ans = 10;
    rep(mask, 1 << 20){
        string t;
        int k = 0;
        each(c, s){
            if(c == 'W' || (mask >> (k++) & 1)){
                t += c;
            }
        }
        int ok = 1, n = sz(t);
        rep(i, n){
            if(t[i] == 'R' && i + kr < n&&t[i + kr] == 'R')ok = 0;
            if(t[i] == 'B' && i + kb < n&&t[i + kb] == 'B')ok = 0;
            if(!ok)break;
        }
        if(ok)smax(ans, n);
    }
    cout << ans << endl;
}