Countdown

Use a while loop to print a countdown from 10 down to 1, then print "Liftoff!" on the last line.

Expected output:

10
9
8
7
6
5
4
3
2
1
Liftoff!

Hints:

• Start with let mut n = 10;
• Loop while n >= 1
• Subtract 1 from n each time
• Print "Liftoff!" after the loop ends