#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main(){
	ll N,A,B; cin >> N >> A >> B;
	ll fac = 1;
	ll ans = 0;
	for(int i = 1; i <= N+1; i++)fac *= i;
	for(ll	i = 0; i <= N; i++){
		ll K; cin >> K;
		ll tmp1 = 1;
		ll tmp2 = 1;
		for(int j = 0; j <= i; j++){
			tmp1 *= A;
			tmp2 *= B;
		}
		ans += K * (tmp2 - tmp1) * (fac / (i+1));
	}
	cout << ans/fac << endl;
}