#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
#define ll long long
#define ull unsigned long long
#define nl '\n'
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define rall(s)  s.rbegin(), s.rend()
#define getline(s) getline(cin>>ws,s)
#define ceill(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define pi  3.141592653589793
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define multi_ordered_set tree<int, null_type,less_equal<int>, rb_tree_tag,tree_order_statistics_node_update>


void Fast_IO(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
// freopen("filename.in", "r", stdin);
// freopen("filename.txt", "w", stdout);
#ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
#endif
}

int dx[8] = { 2, 1, -1, -2, -2, -1, 1, 2 };
int dy[8] = { 1, 2, 2, 1, -1, -2, -2, -1 };
unordered_map<char,bool>omar,sanad;
vector<char> alpha;
vector<ll> score;
double omar_score =0;
void rec(ll fir =0,ll sec=0,int idx=0){
    if(idx == sz(alpha)){
        omar_score+=(fir>sec);
        return;
    }
    if(omar[alpha[idx]]==1){
        rec(fir+score[idx],sec,idx+1);
    }
    if(sanad[alpha[idx]]==1) {
        rec(fir, sec + score[idx], idx + 1);
    }
    if(!omar[alpha[idx]] and !sanad[alpha[idx]]){
        rec(fir + score[idx], sec, idx + 1);
        rec(fir, sec + score[idx], idx + 1);
    }
}



void solve(){
    ll n; cin>>n;
    alpha.resize(n);
    score.resize(n);
    for(auto&i:alpha)cin>>i;
    for(auto&i:score)cin>>i;
    ll m; cin>>m;
    for(int i=0; i<m; i++){
        char c; cin>>c;
        omar[c]=1;
    }
    ll k; cin>>k;
    for(int i=0; i<k; i++){
        char c; cin>>c;
        sanad[c]=1;
    }

    rec();
    cout<<fixed<<setprecision(9);
    cout<<omar_score/(1<<n/2)<<nl;



}

int main(){
    Fast_IO();
    int t =1;
//cin>>t;
    while(t--){
        solve();
    }
    return 0;
}