#include <stdio.h>
#include <stdlib.h>
#include <math.h>
char v[1000000];
int main()
{   FILE*fi,*fout;
    int i,j,con,n,nr,div,flag;
    fi=fopen("numere11.in" ,"r");
    fout=fopen("numere11.out" ,"w");
    fscanf(fi,"%d" ,&n);
    for(i=2;i*i<=n;i++)
      if(v[i]==0)
       for(j=i*i;j<=n;j=j+i)
         v[j]=1;
    con=0;
    for(i=1;i<=n;i++)
    {
       nr=i;
       div=1;
       flag=0;
       while(flag==0&&div<=sqrt(nr))
       {
          if(nr%div==0){
               if(v[div+nr/div]==1)
                flag=1;
          }
          div++;
       }
       if(flag==0)
        con++;
    }
    fprintf(fout,"%d" ,con);
    fclose(fi);
    fclose(fout);
    return 0;
}