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

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