problem27.java

/**
By Lakshmi Narayana V, EIE
*/

public class notpresent {

/** * @param args */public static void main(String[] args) { Scanner s=new Scanner(System.in); int n=s.nextInt(); int arr[]=new int[n]; for(int i=0;i<n;i++) arr[s.nextInt()-1]=1; for(int i=0;i<n;i++) if(arr[i]==0) System.out.println(i+1);}}