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

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

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

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


    return 0;
}