module Fibonacci;

open import Stdlib.Prelude;

fib : ℕ → ℕ → ℕ → ℕ;
fib zero x1 _ ≔ x1;
fib (suc n) x1 x2 ≔ fib n x2 (x1 + x2);

fibonacci : ℕ → ℕ;
fibonacci n ≔ fib n 0 1;

main : IO;
main ≔ putStrLn (natToStr (fibonacci 25));

end;