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.util.Scanner;

public class Main {

    public static void main(String[] args) {
        
        var sc = new Scanner(System.in);
        
        int n = Integer.parseInt(sc.next());
        
        int ans = 0;
        for(int i = 1; i < n; i++){
            int low = 0;
            int high = n;
    
            while(high - low > 1){
                int mid = (low + high) / 2;
                if(ok(mid, i, n)){
                    low = mid;
                }else{
                    high = mid;
                }
            }
            
            int x = Math.max(low - i, 0);
            ans += x * 2;
            if((long) i * (long) i < n) ans += 1;
        }
        System.out.println(ans);
    }
    
    static boolean ok(long mid, long i, long n){
        return mid * i < n;
    }
}