Given is a positive integer N. How many tuples (A,B,C) of positive integers satisfy A \times B + C = N?

Constraints

* 2 \leq N \leq 10^6
* All values in input are integers.

Input

Input is given from Standard Input in the following format:


N


Output

Print the answer.

Examples

Input

3


Output

3


Input

100


Output

473


Input

1000000


Output

13969985
import java.io.*;
import java.util.*;
class Main{

	public static void main(String[] args) {
        FastScanner in = new FastScanner();
        PrintWriter out = new PrintWriter(System.out);
        int n = in.nextInt();
        long cnt = 0;
        for(int i=1;i<n;i++) {
        	for(int j=1;j<n;j++) {
        		if(i*j>=n) break;
        		else cnt++;
        	}
        }
        out.println(cnt);
        out.flush();
	}
	
	static class FastScanner {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer("");
		
		String next() {
			while(!st.hasMoreTokens())
				try {
					st = new StringTokenizer(br.readLine());
				}catch(IOException e) {
					e.printStackTrace();
				}
			return st.nextToken();
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
		
		long nextLong() {
			return Long.parseLong(next());
		}
		
		int[] readArray(int n) {
			int a[] = new int[n];
			for(int i=0;i<n;i++) a[i] = nextInt();
			return a;
		}
		
		Integer[] readArray(long n) {
		    Integer a[] = new Integer[(int)n];
			for(int i=0;i<n;i++) a[i] = nextInt();
			return a;
		}
		
		long[] readArray(int n,long x) {
			long a[] = new long[n];
			for(int i=0;i<n;i++) a[i] = nextLong();
			return a;
		}
		
	}
	
	static class Pair implements Comparable<Pair> {
		int x, y;
		Pair(int a, int b){ x = a; y = b; }
		int getKey() { return x; }
		int getVal() { return y; }
		@Override
		public int compareTo(Pair o) {
			if(o.getVal() - this.getVal()>0)
				return -1;
			else if(o.getVal() - this.getVal()<0)
				return 1;
			else 
				return 0;
		}
		
	}
	
	static boolean arrayEquals(char a[], char b[]) {
		int n = a.length;
		boolean verdict = true;
		for(int i=0;i<n;i++) {
			if(a[i]!=b[i]) {
				verdict = false;break;
			}
		}
		return verdict;
	}
	
	static long lcm(long a, long b) {
		return (a*b)/gcd(a,b);
	}
	
	static long gcd(long a, long b) {
		if(b==0) return a;
		else return gcd(b,a%b);
	}
	
	static long hashInt(int x,int y) {
		return x*(1_000_000_000L)+y;
	}
}
