import java.io.*;

class DamnRabbits {

	static int d;
	static int gb[];
	static int ngb[];
	static int born[];


	public static void main(String[] args) {
		while(true) {
			try {
			main();
			} catch ( IOException e ) {
			}
		}
	}


	public static void main() throws IOException {
		BufferedReader r = new BufferedReader( new InputStreamReader(System.in));

		System.out.print("Number of months? ");
		int n = Integer.parseInt( r.readLine() );
		System.out.print("How long each pair of rabbits live? ");
		d = Integer.parseInt( r.readLine() );


		//keep track
		gb = new int[n + 1];
		ngb = new int[n + 1];
		born = new int[n + 1];
		for (int i = 0; i < n + 1; i++ ) {
			gb[i] = -1;
			ngb[i] = -1;
			born[i] = -1;
		}


		//first month
		gb[1] = 0;
		ngb[1] = 0;
		born[1] = 1;

		System.out.println("There will be " + total(n) + " pairs after " + n + " months.\n\n");
	}



	static int total(int n) {
		return gb(n) + ngb(n) + born(n);
	}



	static int gb(int n) {
		if ( n > 0 ) {
			if ( gb[n] > -1 ) {
				return gb[n];
			} else {
				int toberet = total(n - 1) - born(n - d) - born(n - 1);
				gb[n] = toberet;
				return toberet;
			}
		}
		return 0;
	}



	static int ngb(int n) {
		if ( n > 0 ) {
			if ( ngb[n] > -1 ) {
				return ngb[n];
			} else {
				int toberet = born(n - 1);
				ngb[n] = toberet;
				return toberet;
			}
		}

		return 0;
	}



	static int born(int n) {
		if ( n > 0 ) {
			if ( born[n] > -1 ) {
				return born[n];
			} else {
				int toberet = gb[n];
				born[n] = toberet;
				return toberet;
			}
		}
		return 0;
	}
}