#include <bits/stdc++.h>
#define REP(i, n) for (int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i, s, n) for (int i = (s); i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
using namespace std;
typedef long long ll;

ll  T, K, W, H, M, C, V;
/*
const int MAX = 510000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

vector<double> cx, cy, c;
 ll MM = 1e12;

void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}*/

std::vector<int> Eratosthenes(int n ){
    std::vector<bool> is_prime( n + 1 );
    for( int i = 0; i <= n; i++ ) is_prime[ i ] = true;
    std::vector<int> P;
    for( int i = 2; i <= n; i++ ){
        if( is_prime[ i ] ){
            for( int j = 2 * i; j <= n; j += i ){
                is_prime[ j ] = false;
            }
            P.emplace_back( i );
        }
    }
    return P;
}

bool check(string str, int Kr, int Kb){
    int n = str.size();
    for(int i = 0; i < n; ++i){
        if(str[i] == 'R'){
            if(i + Kr < n){
                if(str[i+Kr] == 'R') return false;
            }
        }
        if(str[i] == 'B'){
            if(i + Kb < n){
                if(str[i+Kb] == 'B') return false;
            }
        }
    }
    return true;
}

int main(){
    int N = 20, Kr, Kb;
    cin >> Kr >> Kb;
    string str;
    cin >> str;
    string t;
    int ans = 10;

    for(int bit = 0; bit < (1<<N) ; ++bit){
        int j = 0, k = 0;
        t.resize(30);
        REP(i, N+10){
            if(str[i] == 'W') t[j++] = 'W';
            else if((bit >> (k++)) % 2 == 1 ) t[j++] = str[i];
        }
        t.resize(j);
        //cout << t << " "<< t.size() << "\n";
        if(check(t, Kr, Kb)) {ans = max(ans, (int)t.size());}
    }
    cout << ans;
    return 0;
}