#include <bits/stdc++.h>
#define x first
#define y second
using namespace std;
typedef long long ll;
const int MAXN = 100500;
const int N = 25;
ll dp[N][N];
ll n, a, b;
int p[N];
ll C[N][N];
ll fact[N];
bool used[N];
double ans[N];

int main()
{
    ios_base::sync_with_stdio(0);
    cin >> n >> a >> b;
    for (int i = 0; i < n; i++)
    {
        cin >> p[i];
        p[i]--;
    }
    fact[0] = 1;
    C[0][0] = 1;
    for (int i = 0; i < N - 1; i++)
    {
        fact[i + 1] = (ll)(i + 1) * fact[i];
        for (int j = 0; j < N - 1; j++)
        {
            C[i + 1][j + 1] += C[i][j];
            C[i + 1][j] += C[i][j];
        }
    }
    for (int i = 1; i <= n; i++)
    {
        dp[i][1] = fact[i - 1];
    }

    for (int sz = 2; sz <= n; sz++)
    {
        for (int i = 1; i <= n; i++)
        {
            for (int k = 1; k <= i; k++)
            {
                dp[i][sz] += dp[i - k][sz - 1] * fact[k - 1] * C[i - 1][k - 1];
            }
        }
    }

    int cur_cycles = 0;
    for (int i = 0; i < n; i++)
    {
        if (!used[i])
        {
            cur_cycles++;
            int j = i;
            while (!used[j])
            {
                used[j] = true;
                j = p[j];
            }
        }
    }

    double best_ans;
    bool is_ba_found = false;
    for (int strat = 1; strat <= n; strat++)
    {
        double lower_res = 0;
        double q = 0;
        for (int c = n; c >= 1; c--)
        {
            if (c >= strat)
            {
                ans[c] = (double)(n - c) * a;
                lower_res += ans[c] * dp[n][c];

            }
            else
            {
                ans[c] = b / q +
            }
        }
        if (best_ans)
    }

    return 0;
}