Mahadevan was puzzled by the strange way in which his granddaughter was counting. She began to count on the fingers of her left hand, calling the thumb 1, the first finger 2, middle finger 3, ring finger 4, little finger 5, then reversed direction, calling the ring finger 6, middle finger 7, first finger 8, thumb 9, then back to the first finger for 10, middle finger for 11, and so on. She continued counting back and forth until she reached a count of 20 on her ring finger. Seeing this, Mahadevan told her that if she could find on which finger she would count 2017, he would buy her an ice cream. Can you find on which finger she will count 2017? Explain the steps.