#include
#include
#include
using namespace std;
typedef long long ll;
int main(){
ll N, X; cin >> N >> X;
string str; cin >> str;
deque dq;
for(int i = 0; i < N; i++){
switch(str[i]) {
case 'U': {
if (dq.size()) dq.pop_back();
else X /= 2;
break;
}
default: {
dq.push_back(str[i]);
break;
}
}
}
while (dq.size()) {
char x = dq.front();
dq.pop_front();
if (x == 'L') X *= 2;
else X = X * 2 + 1;
}
cout << X;
return 0;
}