#include <iostream>
using namespace std;

bool isPrime(int x)
{
    if (x < 2) return false;
    for (int i = 2; i * i <= x; i++)
    {
        if (x % i == 0) 
            return false;
    }
    return true;
}

int main()
{
    int n;
    cin >> n;
    int cnt = 0;
    for (int i = 11; i <= n; i++)
    {
        if (isPrime(i))
        {
            int res = 0, t = i;
            while(t > 0)
            {
                res = res * 10 + t % 10;
                t /= 10;
            }
            if (res == i && isPrime(res)) cnt++;   
        }
    }
    cout << cnt << endl;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int x,y,z,r;
int zs(int c){
	for(int i = 2 ; i <= c - 1 ; i++){
		if(c % i == 0) return 0;
	}
	return c;
}
int dd(int f){
    if(f == 11){
    	r = 11;
	}
	else if(f >= 100){
		x = (f % 10) * 100;
    	y = (f - x / 100) % 100;
    	z = (f - x / 100 - y) / 100;
    	r = x + y + z;
	}
	else r = 0;
	return r;
}
int main(){
	int a,b,e,sum = 0;
	cin >> a;
	for(int i = 11 ; i <= a ; i++){
		b = zs(i);
		if(b == 0) continue;
		e = dd(b);
		if(e == b){
			sum++;
		}
	}
	cout << sum << endl;
	return 0;
}
//11，101，131，151，181，191，313，353，373，383，727，757，787，797，919，929