#include <bits/stdc++.h>
using namespace std;
struct R{
    //de>0
    long long nu,de;
    bool operator<(const R& other) const {
        return (__int128)nu*other.de<(__int128)de*other.nu;
    }
    bool operator==(const R& other) const {
        return (__int128)nu*other.de==(__int128)de*other.nu;
    }
    R operator+(const R& other) const {
        return {nu*other.de+de*other.nu,de*other.de};
    }
    
};
int main(void){
    int n;
    long long a,b;
    cin>>n>>a>>b;
    R ans={0,1};
    for(int i=0;i<=n;i++){
        long long k;
        cin>>k;
        long long ta=1,tb=1;
        for(int j=0;j<=i;j++){
            ta*=a;
            tb*=b;
        }
        ans=ans+(R){k*(tb-ta),i+1};
    }
    if(ans.nu==0){
        cout<<0<<endl;
    }else if(ans.nu<0){
        cout<<-((abs(ans.nu)+ans.de-1)/ans.de)<<endl;
    }else{
        cout<<ans.nu/ans.de<<endl;
    }
    return 0;
}