pub mod procon_input {
    use std::{str::FromStr, iter::FromIterator};

    pub fn read_line() -> String {
        let mut input = String::new();
        std::io::stdin().read_line(&mut input).ok();
        input
    }

    pub fn parse<T: FromStr>(s: &str) -> T {
        s.parse().ok().unwrap()
    }
    
    pub fn read<T: FromStr>() -> T {
        parse(read_line().trim_end())
    }
    
    pub fn read_collection<T: FromStr, C: FromIterator<T>>() -> C {
        read_line().split_whitespace().map(parse).collect()
    }

    #[macro_export]
    macro_rules! read_tuple {
        ( $( $t:ty ),* ) => {{
            let input = read_line();
            let mut iter = input.split_whitespace();
            ( $( parse::<$t>(iter.next().unwrap()) ),* )
        }};
    }
}

use procon_input::*;

fn solve(writer: &mut std::io::BufWriter<std::io::StdoutLock>) {
    use std::io::Write;

    let (n, m, c) = read_tuple!(usize, usize, i64);
    let a: Vec<i64> = read_collection();
    let mut b: Vec<i64> = read_collection();
    b.sort();

    let mut sum = 0;
    for i in 0..n {
        let (mut left, mut right) = (0, m);
        while left < right {
            let middle = (left + right) / 2;
            if a[i] * b[middle] <= c {
                left = middle + 1;
            } else {
                right = middle;
            }
        }
        sum += m - left;
    }
    let ans = sum as f64 / (n * m) as f64;
    writeln!(writer, "{:.}", ans).ok();
}

fn main() {
    let stdout = std::io::stdout();
    let mut writer = std::io::BufWriter::new(stdout.lock());
    solve(&mut writer);
}