use std::io;
use std::io::BufRead;
use std::io::Lines;
use std::io::StdinLock;

#[derive(Debug)]
struct Input {
    yuki_hotel_fee: u32,
    other_hotel_fee: u32,
    count: u32,
    reservations: Vec<u32>
}

fn read_next(iter: &mut Lines<StdinLock>) -> Option<u32> {
    match iter.next() {
        Some(res) => Some(res.unwrap().parse().unwrap()),
        None => None
    }
}

fn create_input() -> Input {
    let mut reservations = Vec::new();
    let stdin = io::stdin();
    let mut lines = stdin.lock().lines();

    let yuki_fee = read_next(&mut lines).unwrap();
    let other_fee = read_next(&mut lines).unwrap();
    let count = read_next(&mut lines).unwrap();

    while let Some(data) = read_next(&mut lines) {
        reservations.push(data);
    }
    Input {yuki_hotel_fee: yuki_fee, other_hotel_fee: other_fee, count: count, reservations: reservations}
}

fn calcurate(input: &Input) -> u32 {
    let target_count: u32 = input.reservations.as_slice().into_iter().sum();
    (input.yuki_hotel_fee + input.other_hotel_fee) * target_count
}

fn main() {
    let input = create_input();
    let result = calcurate(&input);
    println!("{}", result);
}