def bsearch(start, end, number, list):
  if start == end and list[start] == number:
    return start
  if start == end and list[start] != number:
    return -1;
  m = (start+end)/2
  if(list[m] == number):
    return m
  if(list[m] < number):
    return bsearch(m+1,end,number,list)
  if(list[m] > number):
    return bsearch(start,m-1,number,list)