#include <iostream>
#include <string>
using namespace std;

int kr, kb;
string s;

bool is_valid(char block, string blocks) {
    int len = blocks.size();

    if (block == 'W') {
        return true;
    } else if (block == 'R' && (len - kr < 0
                || blocks[len - kr] != 'R'))  {
        return true;
    } else if (block == 'B' && (len - kb < 0
                || blocks[len - kb] != 'B')) {
        return true;
    } else {
        return false;
    }
}

int dfs(int idx, int max_len, string blocks) {
    if (idx == s.size()) {
        return max(max_len, static_cast<int>(blocks.size()));
    }
    if (s.size() - idx + blocks.size() < max_len) {
        return max_len;
    }
    auto res = max_len;
    auto block = s[idx];
    // ひっこぬかないパターン
    if (is_valid(block, blocks)) {
        res = max(res, dfs(idx + 1, res, blocks + block));
    }
    // ひっこぬくパターン
    if (block != 'W') res = max(res, dfs(idx + 1, res, blocks));
    return res;
}

int main() {
    cin >> kr >> kb >> s;

    cout << dfs(0, 0, "") << endl;

    return 0;
}