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

using ll = long long;

int main(){
    ll n,a,b;
    cin >> n >> a >> b;
    ll A=a;
    ll B=b;
    __int128_t d=1;
    for(int i=1;i<=n;i++)d*=i;
    __int128_t ans=0;
    for(int i=1;i<=n+1;i++){
        ll k;
        cin >> k;
        __int128_t x=__int128_t(k)*d/i;
        ans-=x*A;
        ans+=x*B;
        A*=a;
        B*=b;
    }
    if(ans<0){
        ans-=d-1;
    }
    cout << ll(ans/d) << endl;
    return 0;
}