public int findFirstOccurrence(int [] arrA, int x,int start, int end ){
		if(end>=start){
			int mid = (start+end)/2;			
			if((mid==0||(arrA[mid-1]<x)) && arrA[mid]==x){
				return mid;
			}else if(arrA[mid]<x){
				return findFirstOccurrence(arrA, x, mid+1, end);
			}else{
				return findFirstOccurrence(arrA, x, start, mid-1);
				
			}
		}else return -1;
	}