#include <stdio.h>
#include <stdlib.h>
#include <math.h>

char r[8] = {0x1, 0x2, 0x4, 0x8, 0x10, 0x20, 0x40, 0x80};

int main()
{
    int n, i, j, N, nr = 0;
    char a[250001] = {0};
    FILE *in=fopen("ciur.in","r");
    FILE *out=fopen("ciur.out","w");    
    fscanf(in,"%d",&N);

    memset(a, 0xff, 250001);
    n = sqrt(N) + 1;
    for (i = 2; i <= n; i++)
    {
        if (a[i >> 3] & r[i & 0x7]) {    
            for (j = i*i; j <= N; j += i) {
                a[j >> 3] &= ~r[j & 0x7];
                nr++;
            }
        }                                    
    }
    nr = N - nr - 1;
 
    fprintf(out,"%d",nr);
    fclose(in);
    fclose(out);
    return 0;
}