3. Write a function digit(n,k) that returns the digit (from the right) in the positive integer n. For ex-
ample, digit(8345,1) returns 5, digit(8345,2) returns 4, digit(8345,3) returns 3, and digit(8345,4)
returns 8. if k is greater than the number of digits in n, the function must return -1; it means
digit(8345,5) must return -1
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