#include<stdio.h>
int main()
{
    int N,N1 = 1, N2 = 1, total = 0;
    freopen("fractii.in", "r", stdin);
    freopen("fractii.out", "w", stdout);
    scanf("%d", &N);
    if (N >= 1)
    {
        while (N1 <= N)
         {
         if (N2 > N)
          {
           N1++; N2 = 1;
         if (N1 > N)
                  break;
       }
          if (Prime(N1, N2) == 1)
               total++;
               N2++;
        }
    }
    printf("%d\n", total);
    return 0;
}
        int aux1, aux2,max,min;
        double f, h;
        int Prime(int a, int b)
        {
            aux1 = a; aux2 = b;
            if (aux1 == 1 || aux2 == 1)
                return 1;
            else if (aux1 % 2 == 0 && aux2 % 2 == 0)
                return 0;
            else if (aux1 % 3 == 0 && aux2 % 3 == 0)
                return 0;
            else if (aux1 % 5 == 0 && aux2 % 5 == 0)
                return 0;
            else if (aux1 % 7 == 0 && aux2 % 7 == 0)
                return 0;
            else if (aux1 % 11 == 0 && aux2 % 11 == 0)
                return 0;
            else if (aux1 % 13 == 0 && aux2 % 13 == 0)
                return 0;
            else if (aux1 % 17 == 0 && aux2 % 17 == 0)
                return 0;
            else if (aux1 % 19 == 0 && aux2 % 19 == 0)
                return 0;
            else if (aux1 % 23 == 0 && aux2 % 23 == 0)
                return 0;
            else if (aux1 % 27 == 0 && aux2 % 27 == 0)
                return 0;
            else if (aux1 % 29 == 0 && aux2 % 29 == 0)
                return 0;
            else if (aux1 % 31 == 0 && aux2 % 31 == 0)
                return 0;
            else
            {
                max = a > b ? a : b;
                min = a > b ? b : a;
                f = (double)max / (double)min;
                h = f;
                if ((int)f < h)
                    return 1;
                else
                    return 0;
            }
        }