import java.util.*;
import java.lang.*;
import java.io.*;

class Main {
    public static int findSmallestInterval(List<Integer> numbers){
        if(numbers.size()>=2){
            int interval= Math.abs(numbers.get(0)-numbers.get(1));
            for(int i=0; i<numbers.size(); i++){
                for(int j=i+1; j<numbers.size(); j++){
                    int diff=Math.abs(numbers.get(i)-numbers.get(j));
                    interval=Math.min(interval, diff);
                }
            }
            return interval;
        }
        return 0;
    }
    
    public static void main(String[] args) {
        System.out.println(findSmallestInterval(Arrays.asList(1,6,4,8))); 
    }
}