#include <stdio.h>

int bin(int *arr,int l,int h,int k)
{
	int mid;
	if(l>h)
		return -1;
	if(l==h)
	{
		return arr[l]==k?l:-1;
	}
	else
	{
		mid=(l+h)>>1;
		if(arr[mid]==k)
			return mid;
		else if(k>arr[mid])
			bin(arr,mid+1,h,k);
		else
			return bin(arr,l,mid-1,k);
	}
}

int main()
{
	int arr[]={1,3,5,6,9},i,size;
	size=sizeof(arr)/sizeof(arr[0]);
		printf("%d ",bin(arr,0,size-1,6));
	return 0;
}