const int N = 1000005;
int n , a , b , c;
long long x[N];
long long sum[N];
long long dp[N];
int main(){
        scanf("%d" , &n);
        scanf("%d %d %d" , &a , &b , &c);
        for(int i = 1 ; i <= n ; i++){
                scanf("%I64d" , &x[i]);
                sum[i] = sum[i - 1] + x[i];
        }
        ConvexHull hull(1);
        dp[1] = a * x[1] * x[1] + b * x[1] + c;
        hull.insert(2 * a * x[1] , dp[1] + a * x[1] * x[1] - b * x[1]);
        for(int i = 2 ; i <= n ; i++){
                dp[i] = a * sum[i] * sum[i] + b * sum[i] + c;
                dp[i] = max(dp[i] , b * sum[i] + a * sum[i] * sum[i] + c + hull.find(-sum[i]));
                hull.insert(2 * a * sum[i] , dp[i] + a * sum[i] * sum[i] - b * sum[i]);
        }
        printf("%I64d\n" , dp[n]);
        return 0;
}