How long should a hug last?

On my way to work, I saw a kid waiting in front of the doors of prison. A man came out the doors. The man and the kid hugged. I passed by them, they were hugging. I turned my head back: they were hugging. Before going down the stairs to the subway, I looked at them for the last time: they were still hugging, as if 54 seconds were not enough for a hug. I thought of the man and the kid for some time. I thought I'd write about them here. I do it now, 16 hours later, before going to sleep. With nobody to hug, and yet, nothing to complain about.