#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
int main(){
    ll n,a,b;
    cin >> n >> a >> b;
    ll ans = 0;
    vector<ll> aa(n+2,1);
    vector<ll> bb(n+2,1);

    for(ll i = 1; i < n+2; i++){
        aa[i] = aa[i-1] * a;
        bb[i] = bb[i-1] * b;
    }
    ll k;
    ll waru = 1;
    for(ll i = 1; i <= n+1; i++){
        waru *= i;
    }
    ll waru2 = waru;

    for(ll i = 0; i <= n; i++){
        cin >> k;
        ans += k * (bb[i+1] - aa[i+1]) * waru;
        waru /= (i+2);
    }
    

    if(ans < 0){
        if(ans % waru2 == 0)cout << ans / waru2 << '\n';
        else cout << ll(ans / waru2) - 1 << '\n';
    }else cout << ll(ans / waru2) << '\n';


    return 0;
}