Problem:
Score : 100 points

Problem Statement

Given is an integer r.

How many times is the area of a circle of radius r larger than the area of a circle of radius 1?

It can be proved that the answer is always an integer under the constraints given.

Constraints

1 \leq r \leq 100

All values in input are integers.

Input

Input is given from Standard Input in the following format:

r

Output

Print the area of a circle of radius r, divided by the area of a circle of radius 1, as an integer.

Sample Input 1

2

Sample Output 1

4

The area of a circle of radius 2 is 4 times larger than the area of a circle of radius 1.

Note that output must be an integer - for example, 4.0 will not be accepted.

Sample Input 2

100

Sample Output 2

10000

Solution in Rust (1.15.1) (judge verdict: Accepted)

macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let mut s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($iter, $t); input_inner!{$iter $($r)*} }; }
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };

    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };

    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };

    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };

    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
#[warn(dead_code)]
fn sieve_of_eratosthenes(n: usize) -> Vec<usize> {
    // spf:
    // store smallest prime factor of number
    // 最小の素因数を格納
    // is_prime:
    // 配列番号が素数であるかどうかを示す
    let mut spf = vec![None; n + 1];
    let mut is_prime = vec![true; n + 1];
    let mut primes = Vec::new();

    // 0 と 1 は素数ではない
    is_prime[0] = false;
    is_prime[1] = false;

    for i in 2..n + 1 {
        // is_prime[i]:
        // それ以下の素数で割り切られていなければ True となる
        if is_prime[i] {
            // この if 文より i は素数なので
            primes.push(i);

            // 素数はそれ自身の最も小さい素因数であるから
            spf[i] = Some(i);
        }

        // 全ての prime の倍数(prime * i)を取り除く
        for prime in &primes {
            // prime が i の最も小さい因数よりも大きくなってしまったら探索終了
            if i * prime >= n + 1 || prime > &spf[i].unwrap() {
                break;
            }

            is_prime[i * prime] = false;

            // i * primes[j] の最も小さい素数は primes[j] 自身
            spf[i * prime] = Some(*prime);
        }
    }
    primes
}
use std::cmp::Ordering;
#[derive(Eq, PartialEq, Clone, Debug)]
pub struct Rev<T>(pub T);

impl<T: PartialOrd> PartialOrd for Rev<T> {
    fn partial_cmp(&self, other: &Rev<T>) -> Option<Ordering> {
        other.0.partial_cmp(&self.0)
    }
}

impl<T: Ord> Ord for Rev<T> {
    fn cmp(&self, other: &Rev<T>) -> Ordering {
        other.0.cmp(&self.0)
    }
}
fn gcd(a: u64, b: u64) -> u64 {
    if b == 0 {
        a
    } else {
        gcd(b, a % b)
    }
}
fn lcm(a: u64, b: u64) -> u64 {
    a / gcd(a, b) * b
}

#[warn(unused_mut)]
#[warn(unused_imports)]
use std::collections::BTreeSet;
fn main() {
    input! { r: u64};

    println!("{}", r.pow(2));
}