Problem:
Score : 200 points

Problem Statement

Evi has N integers a_1,a_2,..,a_N. His objective is to have N equal integers by transforming some of them.

He may transform each integer at most once. Transforming an integer x into another integer y costs him (x-y)^2 dollars. Even if a_i=a_j (i≠j), he has to pay the cost separately for transforming each of them (See Sample 2).

Find the minimum total cost to achieve his objective.

Constraints

1≦N≦100

-100≦a_i≦100

Input

The input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the minimum total cost to achieve Evi's objective.

Sample Input 1

2
4 8

Sample Output 1

8

Transforming the both into 6s will cost (4-6)^2+(8-6)^2=8 dollars, which is the minimum.

Sample Input 2

3
1 1 3

Sample Output 2

3

Transforming the all into 2s will cost (1-2)^2+(1-2)^2+(3-2)^2=3 dollars. Note that Evi has to pay (1-2)^2 dollar separately for transforming each of the two 1s.

Sample Input 3

3
4 2 5

Sample Output 3

5

Leaving the 4 as it is and transforming the 2 and the 5 into 4s will achieve the total cost of (2-4)^2+(5-4)^2=5 dollars, which is the minimum.

Sample Input 4

4
-100 -100 -100 -100

Sample Output 4

0

Without transforming anything, Evi's objective is already achieved. Thus, the necessary cost is 0.

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

#![allow(unused_imports)]
#![allow(dead_code)]

use std::thread;
use std::io::{ self, Read };
use std::fmt;
use std::iter::Iterator;
use std::cmp::*;
use std::collections::*;
use std::str::*;
use std::mem::*;
use std::cell::*;

struct Input {
    stdin: io::Stdin,
    buf: VecDeque<String>
}

impl Input {
    fn new() -> Input {
        Input { 
            stdin: io::stdin(),
            buf: VecDeque::new()
        }
    }

    fn read<T: FromStr>(&mut self) -> T 
    where <T as FromStr>::Err: fmt::Debug {
        self.next().unwrap().parse::<T>().unwrap()
    }

    fn read_2<T: FromStr, U: FromStr>(&mut self) -> (T, U)
    where <T as FromStr>::Err: fmt::Debug,
          <U as FromStr>::Err: fmt::Debug {
        (self.read(), self.read())
    }

    fn read_3<T: FromStr, U: FromStr, V: FromStr>(&mut self) -> (T, U, V)
    where <T as FromStr>::Err: fmt::Debug,
          <U as FromStr>::Err: fmt::Debug,
          <V as FromStr>::Err: fmt::Debug {
        (self.read(), self.read(), self.read())
    }

    fn read_bytes(&mut self) -> Vec<u8> {
        self.next().unwrap().into_bytes()
    }

    fn read_n<T: FromStr>(&mut self, n: usize) -> Vec<T>
    where <T as FromStr>::Err: fmt::Debug {
        let mut v = Vec::new();
        for _ in 0..n { v.push(self.read::<T>()); }
        v
    }
}

impl Iterator for Input {
    type Item = String;
    fn next(&mut self) -> Option<String> {
        while self.buf.is_empty() {
            let mut s = String::new();
            let _res = self.stdin.read_line(&mut s);
            self.buf.extend(s.split_whitespace().map(|s| s.to_owned()));
        }
        self.buf.pop_front()
    }
}

fn popcnt(x: i64) -> i64 {
    let mut y = 0;
    let mut b = 1;
    while b <= x {
        if x & b > 0 { y += 1; }
        b <<= 1;
    }
    y
}

fn run() {
    let mut ip = Input::new();
    let n = ip.read();
    let a: Vec<i64> = ip.read_n(n);
    let mut ans = 1i64 << 50;
    for x in -100..101 {
        let mut s = 0;
        for &y in &a {
            s += (x - y) * (x - y);
        }
        ans = min(ans, s);
    }
    println!("{}", ans);
}

fn main() {
    let _ = thread::Builder::new()
        .stack_size(50 * 1024 * 1024)
        .spawn(run).unwrap()
        .join();
}