sem6_2

#include <stdio.h>
#define SWAP(type, a, b) {type tmp = a; a = b; b=tmp;}
int bin_search(int* arr, int val, int left, int right)
{
 if((right - left) == 1)
 { 
  if(arr[left] == val)
   return left;
  if(arr[right] == val)
   return right;
  
  return -1;
 }
 int mid = (right + left) / 2;
 if(val > arr[mid])
  return bin_search(arr, val, mid, right);
 else if(val < arr[mid])
  return bin_search(arr, val, left, mid);
 else
  return mid;
}
int main()
{
 int arr[] = {1, 1, 3, 4, 7, 9, 11};
 int val;
 scanf("%d", &val);
 printf("%d\n", bin_search(arr, val, 0, 5));
 return 0;
}