import java.util.*; class Main { public static int returnFirstRec(int[] qstn){ HashMap<Integer, Integer> map = new HashMap(); for(int i=0;i<qstn.length;i++){ if(!map.containsKey(qstn[i])){ map.put(qstn[i], 1); } else{ return qstn[i]; } } return -1; } public static void main(String[] args) { int[] qstn = {2,5,1,2,3,4}; System.out.println(returnFirstRec(qstn)); } }