1-- Compute fibonacci numbers
2
3FUN fib(n) =
4	IF n == 0 THEN 0
5	ELSE IF n == 1 THEN 1
6	ELSE fib(n - 1) + fib(n - 2) FI FI
7
8FUN main() =
9	LET n = READ()
10	IN
11		WRITE(fib(n))
12