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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; cin >> N;
    long long a,b; cin >> a >> b;
    vector<long long> K(N+1);
    for(auto &k : K) cin >> k;

    long long n = 0,d = 1;
    long long x = 1,y = 1;
    for(int i=0; i<=N; i++){
        x *= a,y *= b;
        long long n2 = (y-x)*K.at(i),d2 = i+1;
        long long mul = d*d2;
        n *= mul/d,n2 *= mul/d2;
        n += n2,d = mul;
    }
    cout << n/d << endl;
}