Frosty is trying to find his way to Father Christmas.
He slides along the blue ice paths. He has to slide downhill, so down the screen.
When he finds snowballs he picks them up. He avoids children because when they see him they throw snowballs at him which damages his arms and makes his nose ache. But if he throws a snowball at a child the child just laughs and runs away. So, if he is carrying as least as many snowballs as there are children in a group he can go past, throwing as many snowballs as there are children. If he doesn't have enough snowballs he stops.
How does he get to Father Christmas?