#include <stdio.h>

#define MAX 11

int find(int V,int * A,int N)
{  int l,r,m;
   l = 0;
   r = MAX-1;
   while(l<=r)
   {  m = (l+r)/2;
      if(V==A[m])
       return m;
      if(V<A[m])
       r = m-1;
      else
       l = m+1;
   }
   return -1;
}

main(int argc,char * argv)
{  int A[MAX];
   int i;
   for(i=0;i<MAX;i++)
   {  printf("next> ");
      scanf("%d",&(A[i]));
   }
   printf("%d\n",find(2,A,MAX));
   printf("%d\n",find(12,A,MAX));
}