My Friend Martin (1970)

Self-confident, arrogant Seryozha is not friendly with anyone. His only friend is puppy named Martyn. Yes, and he treats him rudely. But the puppy is lost. Throughout the city, the boy is looking for him, but all unsuccessfully. In the end, kind and helpful people help him to find a puppy. And Sergey understands how difficult it is to be alone without friends.