Input text:

there is a tree in a river. a 2nd river is behind the river. a 3rd river is behind the 2nd river. ground is silver. a 4th river is behind the 3rd river. a 5th river is behind the 4th river. a 6th river is behind the 5th river. a 7th river is behind the 6th river.a 8th river is behind the 7th river. a 9th river is behind the 8th river. a 10th river is behind the 9th river. a 11th river is behind the 10th river.a 12th river is behind the 11th river.