3 is a 1971 children's picture book by American author and illustrator Ezra Jack Keats.

The sound of a harmonica floats through the halls of Sam and Ben's tenement.

The sweet melodies inspire the brothers to explore the building, which is filled with the sounds and smells of a diverse city.

Finally, the brothers find the source of the beautiful music, along with a blind man who “sees” with his ears, and the search ends in a new friendship.

[1] In 1979, the film, narrated by Charles Turner, was released.