#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using mint = modint998244353;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vvvll = vector<vvll>;
using vmi = vector<mint>;
using vvmi = vector<vmi>;
using vvvmi = vector<vvmi>;
#define all(a) (a).begin(), (a).end()
#define rep2(i, m, n) for (int i = (m); i < (n); ++i)
#define rep(i, n) rep2(i, 0, n)
#define drep2(i, m, n) for (int i = (m)-1; i >= (n); --i)
#define drep(i, n) drep2(i, n, 0)

void solve(){
    
}
ll p(ll a, ll n){
    ll w = 1;
    rep(i, n)w *= a;
    return w;
}

int main(){
    int n; ll a, b; cin >> n >> a >> b;
    vll kaijo(12, 1); rep2(i, 2, 12)kaijo[i] = kaijo[i-1]*(ll)i;
    vll k(n+1); rep(i, n+1)cin >> k[i];
    vll s(n+1);
    rep(i, n+1){
        ll c = p(b, i+1) - p(a, i+1);
        s[i] = kaijo[n+1]*k[i]*c / (ll)(i+1); 
    }
    ll t = 0; rep(i, n+1)t += s[i];
    if(t >= 0){
        cout << t/kaijo[n+1] << endl;
    }else{
        if(-t % kaijo[n+1] == 0){
            cout << t/kaijo[n+1] << endl;
        }else{
            cout << t/kaijo[n+1] << endl;
        }
    }


    return 0;
}