//Rabbits.java



//import utils.SavitchIn;


class Rabbits
{
	public static void main(String[] agrs)
	{
		int month;
		System.out.print("\nHow many months: ");
		month =	SavitchIn.readLineInt();
		System.out.println(fibo(month));
	}


	public static int fibo(int month){

		int fibon1 = 0, fibon2 = 1, fibon3;

		for(int i = 0; i < month; i++){
		
			fibon3 = fibon1;
			fibon1 = fibon2;
			fibon2 = fibon1 + fibon3;
		}
		return(fibon1);
	}

}