import java.io.*;
import java.util.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        TreeMap<Integer, Integer> square = new TreeMap<>();
        int idx = 1;
        int target = 1;
        while (target * target <= n) {
            square.put(target * target, idx++);
            target++;
        }
        int root = target - 1;
        int[] counts = new int[n + 1];
        for (int i = 1; i <= n; i++) {
            counts[i] = i;
        }
        boolean[] isNotPrimes = new boolean[root + 1];
        for (int i = 2; i <= root; i++) {
            if (!isNotPrimes[i]) {
                for (int j = 2; j * i <= root; j++) {
                    isNotPrimes[j * i] = true;
                }
                long base = i * i;
                while (base <= n) {
                    int x = (int)base;
                    for (int j = 1; j * base <= n; j++) {
                        counts[j * x] /= i * i;
                    }
                    base *= i * i;
                }
            }
        }
        long ans = 0;
        for (int i = 1; i <= n; i++) {
            ans += square.floorEntry(n / counts[i]).getValue();
        }
        System.out.println(ans);
    }
}

class Utilities {
    static String arrayToLineString(Object[] arr) {
        return Arrays.stream(arr).map(x -> x.toString()).collect(Collectors.joining("\n"));
    }
    
    static String arrayToLineString(int[] arr) {
        return String.join("\n", Arrays.stream(arr).mapToObj(String::valueOf).toArray(String[]::new));
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public int[] nextIntArray() throws Exception {
        return Stream.of(br.readLine().split(" ")).mapToInt(Integer::parseInt).toArray();
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
    
}