import java.util.*;
class ArraySearch{
public static void main(String args[]){
	   int a[]={2,4,5,7,9};
	   int key,pos;
	   key=5;
	   pos=Arrays.binarySearch(a,key);
	   if(pos<0)
	          System.out.println("Ԫ"+key+"в");
	   else
	          System.out.println("Ԫ"+key+"еλΪ"+pos);
}
}