Its something that each of us devours,
Not just us but birds, beats, trees, and flowers,
Frets iron and nibbles steel,
Toil hard stones to meal,
Exterminates king, collapse town,
And blows the mountains down.
What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?