import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int[] a = new int[n];
        for(int a_i=0; a_i < n; a_i++){
            a[a_i] = in.nextInt();
        }
        
        int smallest = Integer.MAX_VALUE;
        int nextSmallest =  Integer.MAX_VALUE;
        
        // find smallest
        for (int i = 0; i < a.length; i++) {
            if (Math.abs(a[i]) < smallest) {
                smallest = Math.abs(a[i]);
            }
        }
        // find next smallest
        for (int i = 0; i < a.length; i++) {
            int current = Math.abs(a[i]);
            if (current < nextSmallest && current > smallest) {
                nextSmallest = current;
            }
        }
        System.out.println(smallest + nextSmallest);
    }
}