Golang monkeys eat peaches and ask for the number of peaches on the first day

/*
 The problem of monkeys eating peaches , There is a pile of peaches , The monkey ate half of it on the first day , And one more ！ Later, every day monkeys eat half of them , And then one more .
 By the tenth day , Want to eat again , Found only one peach . ask ： How many peaches were there at first 

 Thought analysis ：
1.  The first 10 There is only one peach in the sky 
2.  On the ninth day, there were some peaches  = （ The number of peaches on the tenth day  + 1） * 2
3.  law ： The first n Number of peaches per day  peach(n) = (peach(n + 1) + 1) * 2

*/

func peach(n int) int {
	if n > 10 || n < 1 {
		fmt.Println(" The number of days entered is incorrect ")
		return 0 // return 0 Express   Input error 
	}
	if n == 10 {
		return 1
	} else {
		return (peach(n + 1 ) + 1) * 2
	}
	
}
func main() {
	fmt.Println(" The number of peaches in the monkey on the first day was ",peach(1))
}