from typing import Counter


def find_non_overlapping(overlap_count: Counter) -> set:
    """
    Finds all cells that have no overlap and
    returns a set of these cells
    """
    non_overlapping_cells = set()
    for cell, occurences in overlap_count.most_common():
        if occurences == 1:
            non_overlapping_cells.add(cell)

    return non_overlapping_cells