#include<bits/stdc++.h>
#define int long long
using namespace std;
signed main(){
    int N;
    cin>>N;
    string S;
    cin>>S;
    int R=0,B=0;
    for(int i=0;i<N;i++){
        int A;cin>>A;
        if(S[i]=='R')R+=A;
        else B=A;
    }
    cout<<abs(R-B)<<endl;
}