#include <iostream>
#include <string>
#include <queue>
#include <stack>
#include <algorithm>
#include <list>
#include <vector>
#include <complex>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <climits>
#include <bitset>
#include <ctime>
#include <map>
#include <unordered_map>
#include <set>
#include <unordered_set>
#include <cassert>
#include <cstddef>
#include <iomanip>
#include <numeric>
#include <tuple>
#include <sstream>
#include <fstream>
#include <random>

using namespace std;
#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define FOR(i, a, b) for (int (i) = (a); (i) < (b); (i)++)
#define RREP(i, a) for(int (i) = (a) - 1; (i) >= 0; (i)--)
#define FORR(i, a, b) for(int (i) = (a) - 1; (i) >= (b); (i)--)
#define DUMP(C) cerr << #C << " = " << C << endl;
using LL = long long;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<LL>;
using VVL = vector<VL>;
using VD = vector<double>;
using VVD = vector<VD>;
using PII = pair<int, int>;
using PDD = pair<double, double>;
using PLL = pair<LL, LL>;
using VPII = vector<PII>;
template<typename T> using VT = vector<T>;
#define ALL(a) begin((a)), end((a))
#define RALL(a) rbegin((a)), rend((a))
#define SORT(a) sort(ALL((a)))
#define RSORT(a) sort(RALL((a)))
#define REVERSE(a) reverse(ALL((a)))
#define MP make_pair
#define FORE(a, b) for (auto &&a : (b))
#define FIND(s, e) ((s).find(e) != (s).end())
#define EB emplace_back
template<typename T> inline bool chmax(T &a, T b){if (a < b){a = b;return true;}return false;}
template<typename T> inline bool chmin(T &a, T b){if (a > b){a = b;return true;}return false;}

const int INF = 1e9;
const int MOD = INF + 7;
const LL LLINF = 1e18;
const double EPS = 1e-9;
FILE *fp;

void init();
void last();

void init() {
#ifdef MYLOCAL
    if ((fp = freopen("/Users/sekiya9311/Documents/comp_programming/comp_programming/in.txt", "r", stdin)) == nullptr) {
        assert(false);
    }
#endif
}

void last() {
#ifdef MYLOCAL
    fclose(fp);
#endif
    exit(0);
}

const int MAX = 110;
set<int> lose, back;
double dp[MAX][MAX];
void solve(int n, int t, int l, int b) {
    for (int i = 0; i < MAX; i++) {
        for (int j = 0; j < MAX; j++) {
            dp[i][j] = 0.0;
        }
    }
    for (int i = 0; i < l ;i++) {
        int buf;
        scanf("%d", &buf);
        lose.insert(buf);
    }
    for (int i = 0; i < b; i++) {
        int buf;
        scanf("%d", &buf);
        back.insert(buf);
    }
    dp[0][0] = 1.0;
    for (int i = 0; i < t ;i++) {
        for (int j = 0; j < n; j++) {
            for (int dice = 1; dice <= 6; dice++) {
                int next = j + dice;
                if (next > n) next = n + (n - next);
                if (next < 0) next = -next;
                if (lose.count(next)) {
                    dp[i + 2][next] += dp[i][j] / 6.0;
                } else if (back.count(next)) {
                    dp[i + 1][0] += dp[i][j] / 6.0;
                } else {
                    dp[i + 1][next] += dp[i][j] / 6.0;
                }
            }
        }
        dp[i + 1][n] += dp[i][n];
    }
    printf("%.10lf\n", dp[t][n]);
    lose.clear();
    back.clear();
}

signed main(void) {
    LL n, m, p, a, b, c, x, y, z, q;
    string s;
    bool f = false;
    init();
    while (cin >> n >> p >> q >> z, n) {
        solve(n, p, q, z);
        //return 0;
    }
    last();
}

Measured memory_bytes: 3280