#ifdef LOCAL
    #define _GLIBCXX_DEBUG
    #define __clock__
#else
    #pragma GCC optimize("Ofast")
#endif
#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using VI = vector<ll>;
using VV = vector<VI>;
using VS = vector<string>;
using PII = pair<ll, ll>;

// tourist set
template <typename A, typename B>
string to_string(pair<A, B> p);

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p);

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p);

string to_string(const string& s) {
  return '"' + s + '"';
}

string to_string(const char* s) {
  return to_string((string) s);
}

string to_string(bool b) {
  return (b ? "true" : "false");
}

string to_string(vector<bool> v) {
  bool first = true;
  string res = "{";
  for (int i = 0; i < static_cast<int>(v.size()); i++) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(v[i]);
  }
  res += "}";
  return res;
}

template <size_t N>
string to_string(bitset<N> v) {
  string res = "";
  for (size_t i = 0; i < N; i++) {
    res += static_cast<char>('0' + v[i]);
  }
  return res;
}

template <typename A>
string to_string(A v) {
  bool first = true;
  string res = "{";
  for (const auto &x : v) {
    if (!first) {
      res += ", ";
    }
    first = false;
    res += to_string(x);
  }
  res += "}";
  return res;
}

template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}

template <typename A, typename B, typename C>
string to_string(tuple<A, B, C> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ")";
}

template <typename A, typename B, typename C, typename D>
string to_string(tuple<A, B, C, D> p) {
  return "(" + to_string(get<0>(p)) + ", " + to_string(get<1>(p)) + ", " + to_string(get<2>(p)) + ", " + to_string(get<3>(p)) + ")";
}

void debug_out() { cerr << '\n'; }

template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  cerr << " " << to_string(H);
  debug_out(T...);
}

#ifdef LOCAL
#define debug(...) cerr << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
#else
#define debug(...) 42
#endif
// tourist set end

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define rep(i,b) FOR(i, 0, b)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<'\n'
#define p2(s, t) cout << (s) << " " << (t) << '\n'
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << '\n'
#define SZ(x) ((int)(x).size())
#define SORT(A) sort(ALL(A))
#define RSORT(A) sort(ALL(A), greater<ll>())
#define MP make_pair
#define p_yes() p("Yes")
#define p_no() p("No")

ll SUM(VI& V){
  return accumulate(ALL(V), 0LL);
}

ll MIN(VI& V){return *min_element(ALL(V));}
ll MAX(VI& V){return *max_element(ALL(V));}

void print_vector(VI& V){
  ll n = V.size();
  rep(i, n){
    if(i) cout << ' ';
    cout << V[i];
  }
  cout << endl;
}

ll gcd(ll a,ll b){
    if(b == 0) return a;
    return gcd(b,a%b);
}

ll lcm(ll a,ll b){
    ll g = gcd(a,b);
    return a / g * b;
}

// long double
using ld = long double;
#define EPS (1e-14)
#define equals(a,b) (fabs((a)-(b)) < EPS)

void no(){p_no(); exit(0);}
void yes(){p_yes(); exit(0);}

const ll mod = 1e9 + 7;
const ll inf = 1e18;
const double PI = acos(-1);

// Matrix (long double ver)
using Mat = vector<vector<ld>>;
// Matrix Library
Mat mat_mul(const Mat& x, const Mat& y){
    int a = x.size();
    int b = x[0].size();
    int c = y[0].size();
    Mat z(a, vector<ld>(c, 0));
    FOR(i, 0, a){
        FOR(j, 0, c){
            FOR(k, 0, b){
                z[i][j] += x[i][k] * y[k][j];
                //z[i][j] %= mod; // 必要であれば
            }
        }
    }
    return z;
}
Mat mat_pow(const Mat& x, ll k){
    int n = x.size();
    Mat y(n, vector<ld>(n, 0));
    FOR(i, 0, n){
        y[i][i] = 1;
    }
    auto z = x;
    if(k==0) return y;
    if(k==1) return z;

    if(k%2==0){
        return mat_pow(mat_mul(x, x), k/2);
    }else{
        return mat_mul(x, mat_pow(x, k-1));
    }
}
void print_mat(Mat x){
    ll H = x.size();
    FOR(i, 0, H){
        for(ld v : x[i]){
          cout << v << ' ';
        }
        cout << endl;
    }
}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    ll N,M,K;
    cin>>N>>M>>K;

    ld p,q;cin>>p>>q;

    VI B(N);
    rep(i, N) cin >> B[i];

    ld warp = p/q;
    ld stay = 1-warp;
    Mat A = {
      {stay, warp},
      {warp, stay}
    };
    print_mat(A);
    Mat P = mat_pow(A, K);

    // (1, 0) : 存在から開始
    Mat I = {
      {1},
      {0}
    };
    // (0, 1) : コップ外から開始
    Mat J = {
      {0},
      {1}
    };
    ld exist_to_exist = mat_mul(P, I)[0][0];
    ld out_to_exist = mat_mul(P, J)[0][0];

    ld sum = 0;
    rep(i,M){
      sum += B[i] * exist_to_exist;
    }
    FOR(i, M, N){
      sum += B[i] * out_to_exist;
    }
    cout << setprecision(20);
    p(sum);
    
    return 0;
}