#include <iostream>
using namespace std;
int kr, kb;
char s[31];
int rec(int i, int r, int b){
    if(i == 30) return __builtin_popcount(r) + __builtin_popcount(b);
    if(s[i] == 'W') return rec(i+1, r<<1, b<<1);
    int res = rec(i+1, r, b);
    if(s[i]=='R' && !(r&1<<(kr-1))) res = max(res, rec(i+1, r<<1|1, b<<1));
    if(s[i]=='B' && !(b&1<<(kb-1))) res = max(res, rec(i+1, r<<1, b<<1|1));
    return res;
}
int main(){
    cin >> kr >> kb;
    cin >> s;
    cout << 10 + rec(0, 0, 0) << endl;
    return 0;
}