C++ :

#include<bits/stdc++.h>
using namespace std;
 
typedef long long LL;
const LL imx=1e12;
LL n,id,cnt;
char ch;
 
int main() {
    cin>>n>>id;
    while(n--) {
        cin>>ch;
        if(ch=='U') {
            if(cnt!=0) {
                cnt--;
                continue;
            }
            if(id!=1) id=id/2;
        } 
		else if(ch=='L') {
            if(id*2>imx) cnt++;
            else id=id*2;
        } 
		else {
            if(id*2>imx) cnt++;
            else id=id*2+1;
        }
    }
    cout<<id<<endl;
    return 0;
}
 
/*
in:
3 2
URR
out:
7
*/