import java.io.IOException;
import java.util.Scanner;

public class Main {
	public static void main(String[] args)throws IOException {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		boolean[] x = new boolean[1000001];

		for (int i=0;i<n;i++){
			x[sc.nextInt()] = true;
		}

		int maxi = 1000001;

		for (int i=0;i<1000000;i++){
			if(x[i]){
				for(int j=i+1;j<Math.min(1000001,i+maxi);j++){
					if(x[j]){
						maxi = j-i;
					}
				}
			}
		}

		if(maxi == 1000001){ maxi = 0; }
		System.out.println(maxi);
	}
}