Disorder

gistfile1.java

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
	
	public static void main(String [] args) throws IOException {

		//Scanner sc = new Scanner(new File("data.txt"));
		
		Scanner sc = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		
		while (sc.hasNextInt()) {
			int ammount = sc.nextInt();
			
			
			int [] nums = new int[ammount];
			int index = 0;
			
			while (ammount > 0) {
				--ammount;
				nums[index++] = sc.nextInt();
			}

			Arrays.sort(nums);

			
			int res = 0;
			for (int i = 0; i < nums.length; ++i) {
				int num = i+1;

				if (num != nums[i]) {
					res = num;
					break;
				}
			}

			
			out.println(res);
			out.flush();
		}
		
		
		
		
		

	}

}