#![allow(dead_code, unused_variables)]
use std::io::{stdin, BufRead};

fn solve(w: i32, z: i32, b: f32) -> i32 {
    ((w + z) as f32 * (b + 1.0)).round() as i32
}

fn main() {
    let v = vecwords_from_line();
    println!(
        "{}",
        solve(
            v[0].parse().unwrap(),
            v[1].parse().unwrap(),
            v[2].parse().unwrap()
        )
    );
}

fn get_line() -> String {
    let mut buf = String::new();
    stdin().lock().read_line(&mut buf).unwrap();
    buf.trim_end().to_string()
}

fn get_number<T>() -> T
where
    T: std::str::FromStr,
    T::Err: std::fmt::Debug,
{
    get_line().parse().unwrap()
}

fn veci32_from_line() -> Vec<i32> {
    get_line()
        .split_whitespace()
        .map(|s| s.parse().unwrap())
        .collect()
}

fn vecwords_from_line() -> Vec<String> {
    get_line()
        .split_whitespace()
        .map(|s| s.to_string())
        .collect()
}