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

int prime_data[168] = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53,
    59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137,
139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227,
229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313,
317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419,
421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509,
521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617,
619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727,
733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829,
839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947,
953, 967, 971, 977, 983, 991, 997};

int num_factor[1000000+1]={0};

int result[1000000+1]={0};

int main(){
	int count=0;
	int i;
	int j;
	int n;
	for(i=0; i<168; i++) {
        num_factor[prime_data[i]] = prime_data[i];
        for(j=prime_data[i]*prime_data[i]; j <= 1000000; j+=prime_data[i])
            num_factor[j] = prime_data[i];
    }
	/*for(i=0;i<168;i++){
		num_factor[prime_data[i]] = prime_data[i];
		for(j=prime_data[i]*prime_data[i];j<=1000000;j+=prime_data[i])
			num_factor[j]=prime_data[i];
	}*/
	int num;
	result[1]=0;
	result[2]=1;
	int temp;
	for(i=3;i<=1000000;i++){
		count = 0;
		temp = i;
		while(temp!=1){
			if(num_factor[temp]==0){
				num_factor[temp]++;
				break;
			}
			temp/=num_factor[temp];
			count++;
		}
		result[i] = result[i-1]+count;
	}
	while(scanf("%d",&num)){
		printf("%d\n",result[num]);
	}


	return 0;
}