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

long long intpow(long long a, long long b){ 
    long long ans = 1; 
    while(b){ 
        if(b & 1) ans *= a; 
        a *= a; 
        b >>= 1; 
    } 
    return ans;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n, a, b;
    cin >> n >> a >> b;
    vector<long double> p(n);
    long double ans = 0, am = 1, bm = 1, v;
    for(int i = 0; i <= n; i++){
        cin >> v;
        am *= a, bm *= b;
        ans += (long double)(v * (bm - am)) / (i + 1);
    }
    cout << floor(ans) << '\n';
}