#[macro_export]
macro_rules! setup {
    { mut $input:ident: SplitWhitespace $(,)? } => {
        use std::io::Read;
        let mut buf = String::new();
        std::io::stdin().read_to_string(&mut buf).ok();
        let mut $input = buf.split_whitespace();
    };
}

#[macro_export]
macro_rules! parse_next {
    ($str_iter:expr) => {
        $str_iter.next().unwrap().parse().ok().unwrap()
    };
}

fn main() {
    setup! { mut input: SplitWhitespace };

    let n: usize = parse_next!(input);
    let m: usize = parse_next!(input);
    let p: f64 = parse_next!(input);

    let ans = (|| {
        let mut expv = 0.0;
        match (n, m) {
            (1, 1) => {
                expv += p;
            }
            (1, m) => {
                expv += (p * p) * (2 as f64);
                expv += (p * (p * p)) * ((m - 2) as f64);
            }
            (n, 1) => {
                expv += (p * p) * (2 as f64);
                expv += (p * (p * p)) * ((n - 2) as f64);
            }
            (n, m) => {
                let corner = 4;
                let edge = (n - 2) * 2 + (m - 2) * 2;
                let inner = (n - 2) * (m - 2);
                expv += (p * (p * p)) * (corner as f64);
                expv += (p * (p * p * p)) * (edge as f64);
                expv += (p * (p * p * p * p)) * (inner as f64);
            }
        }
        expv
    })();

    println!("{}", ans);
}