백준 - 1037

https://www.acmicpc.net/problem/1037

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int[] arr = new int[n];
        for (int i = 0; i < n; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);
        int answer = arr[0] * arr[arr.length - 1];
        System.out.println(answer);
    }
}