array = [1,3,6,10,15,32,43,46,100,150,170,290] # Given
def BinarySearch(array, target):
    n = len(array)  # length of array.
    left = 0        # at starting are search space is
    right = n-1     # full array(from index 0 to n-1)


    # Now remember what we talk about condition for search.
    # If are left and right index are same or they are at same positon
    # It is time to stop.
    # which also means that are left index should not cross right index.


    while left <= right:
        mid = (left + right)//2 # middle point we talked about

        if array[mid] == target:
            return mid # returning the index vaue

        elif array[mid] < target:
            left = mid+1 # now your search space is halfed.

        else:
            right = mid-1 # now your search space is halfed
    return 'Element does not exist.'