def BinarySearch(alist, target):
    low, high = 0, len(alist)-1
    while low <= high:
        mid = (low+high)/2
        mid_val = alist[mid]
        if mid_val > target:
            high = mid - 1
        elif mid_val < target:
            low = mid + 1
        else:
            return mid
    return -1
 
print BinarySearch([1,2,3,5,8,9], 5)
#//python/7679