ProbA

(*biblioteca para inteiros grandes*)
open Big_int;;

(*ler o indíce*)
let index = read_int();;
let index2 = big_int_of_int index;;


(*Sequência de Perrin*)
let rec perr n = if n=0 then 3 else if n=1 then 0 else if n=2 then 2 else (big_int_of_int (perr(n-2)))+(big_int_of_int (perr(n-3)));;

(*Resultado*)
print_endline(string_of_big_int(perr(index2)));;