#include<stdio.h>
void main( )
{
int a[10]={15,14,13,12,11,10,9,8,7,6};
int l=0,h=9,flag=0,x,mid;
scanf("x=%d",&x);
while(l<=h)
{
mid=(l+h)/2;
if (x==a[mid])
{
printf("the inset num is a[%d]=%d\n",mid,x);
flag=1;
break;
}
else if (x>a[mid])
h=mid-1;
else
l=mid+1;
}
if (flag==0)
printf("no found!\n");
}