import java.io.*;
import java.util.*;
 
public class Main {
 
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		InputReader scn = new InputReader(System.in);
		OutputWriter out = new OutputWriter(System.out);
		int L = scn.nextInt();
      int R = scn.nextInt();
		int d = scn.nextInt();
	long ans = 0;
      for(int i = L; i <= R; i++){
      	if(i % d == 0){
        	ans++;
        }
      
      }
      out.println(ans);
		out.close();
	}
 
	public static boolean CountFrequencies(String[] arr) {
		HashMap<String, Integer> map = new HashMap<>();
		for (int i = 0; i < arr.length; i++) {
			String a = arr[i];
			if (map.containsKey(a)) {
				map.put(a, map.get(a) + 1);
			} else {
				map.put(a, 1);
			}
		}
		for (String val : map.keySet()) {
			String val1 = val;
			int val2 = map.get(val);
			if (val2 % 2 != 0) {
				return false;
			}
		}
		return true;
	}
 
	static class InputReader {
		private InputStream stream;
		private byte[] buf = new byte[1024];
		private int curChar;
		private int numChars;
		private SpaceCharFilter filter;
 
		public InputReader(InputStream stream) {
			this.stream = stream;
		}
 
		public int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}
 
		public int nextInt() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			int res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public long nextLong() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			int sgn = 1;
			if (c == '-') {
				sgn = -1;
				c = read();
			}
			long res = 0;
			do {
				if (c < '0' || c > '9')
					throw new InputMismatchException();
				res *= 10;
				res += c - '0';
				c = read();
			} while (!isSpaceChar(c));
			return res * sgn;
		}
 
		public String nextLine() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}
 
		public boolean isSpaceChar(int c) {
			if (filter != null)
				return filter.isSpaceChar(c);
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}
 
		public String next() {
			return nextLine();
		}
 
		public interface SpaceCharFilter {
			public boolean isSpaceChar(int ch);
		}
	}
 
	static class OutputWriter {
		private final PrintWriter writer;
 
		public OutputWriter(OutputStream outputStream) {
			writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
		}
 
		public OutputWriter(Writer writer) {
			this.writer = new PrintWriter(writer);
		}
 
		public void print(Object... objects) {
			for (int i = 0; i < objects.length; i++) {
				if (i != 0) {
					writer.print(' ');
//                    writer.print(1);
				}
				writer.print(objects[i]);
			}
		}
 
		public void println(Object... objects) {
			print(objects);
			writer.println();
		}
 
		public void close() {
			writer.close();
		}
	}
 
}

Measured memory_bytes: 25532