def binary_search(i,vals):
   min=0
   midpoint=(vals.__len__()/2).__int__()
   max=vals.__len__()
   while min<max:
       if vals[midpoint]==i:
           return midpoint
       if vals[midpoint]>i:
           max=midpoint
       else:
           min=midpoint+1
       midpoint=((min+max)/2).__int__()
   return -1