# include <algorithm>
using namespace std ;

const char FIN[] = "scmax.in", FOU[] = "scmax.out" ;
const int MAX = 100005 ;

int N, sol = 1 ;

int modulo(int a,int b,int c){
    long long x=1,y=a; // long long is taken to avoid overflow of intermediate results
    while(b > 0){
        if(b%2 == 1){
            x=(x*y)%c;
        }
        y = (y*y)%c; // squaring the base
        b /= 2;
    }
    return x%c;
}
long long mulmod(long long a,long long b,long long c){
    long long x = 0,y=a%c;
    while(b > 0){
        if(b%2 == 1){
            x = (x+y)%c;
        }
        y = (y*2)%c;
        b /= 2;
    }
    return x%c;
}
int calculateJacobian(long long a,long long n){
    if(!a) return 0; // (0/n) = 0
    int ans=1;
    long long temp;
    if(a<0){
        a=-a;    // (a/n) = (-a/n)*(-1/n)
        if(n%4==3) ans=-ans; // (-1/n) = -1 if n = 3 ( mod 4 )
    }
    if(a==1) return ans; // (1/n) = 1
    while(a){
        if(a<0){
            a=-a;    // (a/n) = (-a/n)*(-1/n)
            if(n%4==3) ans=-ans;    // (-1/n) = -1 if n = 3 ( mod 4 )
        }
        while(a%2==0){
            a=a/2;    // Property (iii)
            if(n%8==3||n%8==5) ans=-ans;
        }
        swap(a,n);    // Property (iv)
        if(a%4==3 && n%4==3) ans=-ans; // Property (iv)
        a=a%n; // because (a/p) = (a%p / p ) and a%pi = (a%n)%pi if n % pi = 0
        if(a>n/2) a=a-n;
    }
    if(n==1) return ans;
    return 0;
}

/* Iterations determine the accuracy of the test */
bool Solovoy(long long p,int iteration){
    if(p<2) return false;
    if(p!=2 && p%2==0) return false;
    for(int i=0;i<iteration;i++){
        long long a=rand()%(p-1)+1;
        long long jacobian=(p+calculateJacobian(a,p))%p;
        long long mod=modulo(a,(p-1)/2,p);
        if(!jacobian || mod!=jacobian){
            return false;
        }
    }
    return true;
}

int main ( void ) {
      freopen ( "ciur.in", "r", stdin ) ;
      freopen ( "ciur.out", "w", stdout ) ;
      scanf ( "%d", &N ) ;
      for ( int i = 3; i <= N; i += 2 ) {
          if ( Solovoy ( i, 1 ) ) {
              ++sol ;
          }
      }

      printf ( "%d", sol ) ;

}