def toys(w):
    count = 0
    w.sort()
    N = len(w)
    i = 0

    while i < N:
        # The weight of the current toy.
        current_toy_weight = w[i]
        
        # We need at least one container, so we increment the count.
        count += 1
        
        # We can fit any toy with a weight up to 4 units greater than the first toy in the container.
        limit = current_toy_weight + 4
        
        # We find how many toys fit in this container.
        while i < N and w[i] <= limit:
            i += 1
            
    return count