stablegradients/pie-gem5-pairs huggingface dataset:
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<cmath>

using namespace std;



bool prime[1000000];



int main()

{

    int i,j,k,l,m,n;

    int count;

    while(cin>>n)

    {

        memset(prime,0,sizeof(prime));

        prime[1]=1;

        prime[2]=0;



        count=0;



        for(j=2;j*j<=n;j++)

        {

            if(prime[j]==0)

            {

                for(k=2;k*j<=n;k++)

                {

                   prime[j*k]=1;

                }

            }

        }

        for(i=1;i<=n;i++)

        {

            if(prime[i]==0)

            count++;

        }

        cout << count << endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.265260814170884x):
#include<iostream>

#include<cstdio>

#include<cmath>

#define size 20000000

using namespace std;

int find_prime(int n)

{

    int count =0;

    bool *numberList=new bool[size+1];

    for(unsigned long i=3;i<=sqrt(n);i+=2)

    {

        for(unsigned long j=i;i*j<=n;j+=2)

            numberList[i*j]=true;

    }

    for (unsigned long i=3;i<=n;i+=2)

    {

        if(!numberList[i])

            count++;

    }



    return count;



}

int main ()

{

    int n;

    while((scanf("%d",&n))!=EOF)

    {

        if(n==1||n==0)

            printf("0\n");

        else if(n==2)

            printf("1\n");



        else

        {

        int v=0;

        v=find_prime(n);

        printf("%d\n",v+1);

        }

    }

    return 0;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<math.h>

using namespace std;

const int MAX = 1000000;

int prime(int n)

{

	int ans = 0;

	bool prime[MAX];

	memset(prime, 0, sizeof(prime));

	for (int i = 2; i < n;i++)  

	{ 

		for (int j = 2; j <= n / i; j++)

		{

			if (i*j <= n)

				prime[i*j] = 1;

		}

	}

	for (int i = 2; i <= n; i++)

	{

		if (!prime[i])

			ans++;

	}

	return ans;

}

int main()

{

	int n, m = 0;

	while (cin >> n&&m<30)

	{

		cout << prime(n) << endl;

		m++;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.280092467876057x):
#include<iostream>

#include<cstdio>

#include<cmath>

#define size 20000000

using namespace std;

int find_prime(int n)

{

    int count =0;

    bool *numberList=new bool[size+1];

    for(unsigned long i=3;i<=sqrt(n);i+=2)

    {

        for(unsigned long j=i;i*j<=n;j+=2)

            numberList[i*j]=true;

    }

    for (unsigned long i=3;i<=n;i+=2)

    {

        if(!numberList[i])

            count++;

    }



    return count;



}

int main ()

{

    int n;

    while((scanf("%d",&n))!=EOF)

    {

        if(n==1||n==0)

            printf("0\n");

        else if(n==2)

            printf("1\n");



        else

        {

        int v=0;

        v=find_prime(n);

        printf("%d\n",v+1);

        }

    }

    return 0;

}
// Slower C++ solution:
#include<stdio.h>

#include<math.h>

bool flag[1000000];

int main(void)

{

	long long i,j,p,n,count;

	p = (long long)sqrt(1000000.0);

	for(i = 3; i <= p; i = i + 2)

	{

		if(flag[i] == false)

		{

			for(j = i * i; j <= 1000000; j = j + 2 * i)

			{

				flag[j] = true;

				

			}

		}

	}

		

	while((scanf("%lld",&n)) != EOF)

	{

		

		if(n == 1 || n == 0)

			count = 0;

		else

		{

			count = 1;

			for(i = 3; i <= n; i = i + 2)

			{

				if(flag[i] == false)

					count++;

			}

		}

		printf("%lld\n",count);

	}

	



		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 3.4652952636486454x):
#include<iostream>

using namespace std;

bool Eratosthenes[999999+30];



int main()

{

    int n,pos;

    int c;



    while(cin>>n)

    {

        c=0;

        Eratosthenes[1]=false;



        for(int i=2; i<=n; i++) Eratosthenes[i]=true;

        for(int i=2; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

            {

                pos=2*i;

                while(pos<=n)

                {

                    Eratosthenes[pos]=false;

                    pos=pos+i;

                }

            }

        }

        for(int i=1; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

                c++;

        }

        cout<<c<<endl;



    }

    return 0;

}
// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <string>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <vector>

#include <queue>

using namespace std;

#define MAX 1000000

#define LMT 1000

unsigned flag[MAX>>6];

int primes[6000000];//5761455

#define ifc(n) (flag[n>>6]&(1<<((n>>1)&31)))

#define isc(n) (flag[n>>6]|=(1<<((n>>1)&31)))



int sieve()

{

    unsigned i, j, k;

    for(i=3; i<LMT; i+=2)

        if(!ifc(i))

            for(j=i*i, k=i<<1; j<MAX; j+=k)

                isc(j);

    return 0;

}



int main()

{

    sieve();

    unsigned int i,L;

    int k=1, count;

    primes[0]=2;

    while(scanf("%d", &L)==1)

    {

        count=1;

        for( i=3; i<=L; i+=2)

        {

            if(ifc(i)==0)

                count++;

        }

        if(L>1)

            printf("%d\n", count);

        else printf("0\n");

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.3687707319249007x):
#include<iostream>

using namespace std;

bool Eratosthenes[999999+30];



int main()

{

    int n,pos;

    int c;



    while(cin>>n)

    {

        c=0;

        Eratosthenes[1]=false;



        for(int i=2; i<=n; i++) Eratosthenes[i]=true;

        for(int i=2; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

            {

                pos=2*i;

                while(pos<=n)

                {

                    Eratosthenes[pos]=false;

                    pos=pos+i;

                }

            }

        }

        for(int i=1; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

                c++;

        }

        cout<<c<<endl;



    }

    return 0;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<cmath>

using namespace std;



bool prime[1000000];



int main()

{

    int i,j,k,l,m,n;

    int count;

    while(cin>>n)

    {

        memset(prime,0,sizeof(prime));

        prime[1]=1;

        prime[2]=0;



        count=0;



        for(j=2;j*j<=n;j++)

        {

            if(prime[j]==0)

            {

                for(k=2;k*j<=n;k++)

                {

                   prime[j*k]=1;

                }

            }

        }

        for(i=1;i<=n;i++)

        {

            if(prime[i]==0)

            count++;

        }

        cout << count << endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.2569500796328117x):
#include<iostream>

using namespace std;

bool Eratosthenes[999999+30];



int main()

{

    int n,pos;

    int c;



    while(cin>>n)

    {

        c=0;

        Eratosthenes[1]=false;



        for(int i=2; i<=n; i++) Eratosthenes[i]=true;

        for(int i=2; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

            {

                pos=2*i;

                while(pos<=n)

                {

                    Eratosthenes[pos]=false;

                    pos=pos+i;

                }

            }

        }

        for(int i=1; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

                c++;

        }

        cout<<c<<endl;



    }

    return 0;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<math.h>

using namespace std;

const int MAX = 1000000;

int prime(int n)

{

	int ans = 0;

	bool prime[MAX];

	memset(prime, 0, sizeof(prime));

	for (int i = 2; i < n;i++)  

	{ 

		for (int j = 2; j <= n / i; j++)

		{

			if (i*j <= n)

				prime[i*j] = 1;

		}

	}

	for (int i = 2; i <= n; i++)

	{

		if (!prime[i])

			ans++;

	}

	return ans;

}

int main()

{

	int n, m = 0;

	while (cin >> n&&m<30)

	{

		cout << prime(n) << endl;

		m++;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.271727319322639x):
#include<iostream>

using namespace std;

bool Eratosthenes[999999+30];



int main()

{

    int n,pos;

    int c;



    while(cin>>n)

    {

        c=0;

        Eratosthenes[1]=false;



        for(int i=2; i<=n; i++) Eratosthenes[i]=true;

        for(int i=2; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

            {

                pos=2*i;

                while(pos<=n)

                {

                    Eratosthenes[pos]=false;

                    pos=pos+i;

                }

            }

        }

        for(int i=1; i<=n; i++)

        {

            if(Eratosthenes[i]==true)

                c++;

        }

        cout<<c<<endl;



    }

    return 0;

}
// Slower C++ solution:
#include<stdio.h>

#include<math.h>

bool flag[1000000];

int main(void)

{

	long long i,j,p,n,count;

	p = (long long)sqrt(1000000.0);

	for(i = 3; i <= p; i = i + 2)

	{

		if(flag[i] == false)

		{

			for(j = i * i; j <= 1000000; j = j + 2 * i)

			{

				flag[j] = true;

				

			}

		}

	}

		

	while((scanf("%lld",&n)) != EOF)

	{

		

		if(n == 1 || n == 0)

			count = 0;

		else

		{

			count = 1;

			for(i = 3; i <= n; i = i + 2)

			{

				if(flag[i] == false)

					count++;

			}

		}

		printf("%lld\n",count);

	}

	



		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 3.510327950597664x):
#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e7+1;

int prime[maxn];

bool is_prime[maxn];



int sieve(int n) {

    int p = 0;

    for(int i = 1; i <= n; i ++) is_prime[i] = true;

    is_prime[0] = is_prime[1] = false;

    for(int i = 2; i <= n; i ++) {

        if(is_prime[i]) {

            prime[p++] = i;

            for(int j = i+i; j <= n; j += i) {

                is_prime[j] = false;

            }

        }

    }

    return p;

}



int main() {

    int n;

    while(scanf("%d", &n) != EOF) {

        printf("%d\n", sieve(n));

    }

    return 0;

}
// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <string>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <vector>

#include <queue>

using namespace std;

#define MAX 1000000

#define LMT 1000

unsigned flag[MAX>>6];

int primes[6000000];//5761455

#define ifc(n) (flag[n>>6]&(1<<((n>>1)&31)))

#define isc(n) (flag[n>>6]|=(1<<((n>>1)&31)))



int sieve()

{

    unsigned i, j, k;

    for(i=3; i<LMT; i+=2)

        if(!ifc(i))

            for(j=i*i, k=i<<1; j<MAX; j+=k)

                isc(j);

    return 0;

}



int main()

{

    sieve();

    unsigned int i,L;

    int k=1, count;

    primes[0]=2;

    while(scanf("%d", &L)==1)

    {

        count=1;

        for( i=3; i<=L; i+=2)

        {

            if(ifc(i)==0)

                count++;

        }

        if(L>1)

            printf("%d\n", count);

        else printf("0\n");

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.399553710779192x):
#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e7+1;

int prime[maxn];

bool is_prime[maxn];



int sieve(int n) {

    int p = 0;

    for(int i = 1; i <= n; i ++) is_prime[i] = true;

    is_prime[0] = is_prime[1] = false;

    for(int i = 2; i <= n; i ++) {

        if(is_prime[i]) {

            prime[p++] = i;

            for(int j = i+i; j <= n; j += i) {

                is_prime[j] = false;

            }

        }

    }

    return p;

}



int main() {

    int n;

    while(scanf("%d", &n) != EOF) {

        printf("%d\n", sieve(n));

    }

    return 0;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<cmath>

using namespace std;



bool prime[1000000];



int main()

{

    int i,j,k,l,m,n;

    int count;

    while(cin>>n)

    {

        memset(prime,0,sizeof(prime));

        prime[1]=1;

        prime[2]=0;



        count=0;



        for(j=2;j*j<=n;j++)

        {

            if(prime[j]==0)

            {

                for(k=2;k*j<=n;k++)

                {

                   prime[j*k]=1;

                }

            }

        }

        for(i=1;i<=n;i++)

        {

            if(prime[i]==0)

            count++;

        }

        cout << count << endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.2862799111948857x):
#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e7+1;

int prime[maxn];

bool is_prime[maxn];



int sieve(int n) {

    int p = 0;

    for(int i = 1; i <= n; i ++) is_prime[i] = true;

    is_prime[0] = is_prime[1] = false;

    for(int i = 2; i <= n; i ++) {

        if(is_prime[i]) {

            prime[p++] = i;

            for(int j = i+i; j <= n; j += i) {

                is_prime[j] = false;

            }

        }

    }

    return p;

}



int main() {

    int n;

    while(scanf("%d", &n) != EOF) {

        printf("%d\n", sieve(n));

    }

    return 0;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<math.h>

using namespace std;

const int MAX = 1000000;

int prime(int n)

{

	int ans = 0;

	bool prime[MAX];

	memset(prime, 0, sizeof(prime));

	for (int i = 2; i < n;i++)  

	{ 

		for (int j = 2; j <= n / i; j++)

		{

			if (i*j <= n)

				prime[i*j] = 1;

		}

	}

	for (int i = 2; i <= n; i++)

	{

		if (!prime[i])

			ans++;

	}

	return ans;

}

int main()

{

	int n, m = 0;

	while (cin >> n&&m<30)

	{

		cout << prime(n) << endl;

		m++;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.3012491861250868x):
#include <bits/stdc++.h>

using namespace std;

const int maxn = 1e7+1;

int prime[maxn];

bool is_prime[maxn];



int sieve(int n) {

    int p = 0;

    for(int i = 1; i <= n; i ++) is_prime[i] = true;

    is_prime[0] = is_prime[1] = false;

    for(int i = 2; i <= n; i ++) {

        if(is_prime[i]) {

            prime[p++] = i;

            for(int j = i+i; j <= n; j += i) {

                is_prime[j] = false;

            }

        }

    }

    return p;

}



int main() {

    int n;

    while(scanf("%d", &n) != EOF) {

        printf("%d\n", sieve(n));

    }

    return 0;

}
// Slower C++ solution:
#include<stdio.h>

#include<math.h>

bool flag[1000000];

int main(void)

{

	long long i,j,p,n,count;

	p = (long long)sqrt(1000000.0);

	for(i = 3; i <= p; i = i + 2)

	{

		if(flag[i] == false)

		{

			for(j = i * i; j <= 1000000; j = j + 2 * i)

			{

				flag[j] = true;

				

			}

		}

	}

		

	while((scanf("%lld",&n)) != EOF)

	{

		

		if(n == 1 || n == 0)

			count = 0;

		else

		{

			count = 1;

			for(i = 3; i <= n; i = i + 2)

			{

				if(flag[i] == false)

					count++;

			}

		}

		printf("%lld\n",count);

	}

	



		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 3.468043817432087x):
#include<cstdio>

#include<iostream>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<cstdlib>

#include<ctime>

#include<stack>

#include<queue>

#include<set>

#include<map>

#include<vector>

#define mem(name,value) memset(name,value,sizeof(name))

#define loop(i,from,to) for(int i=from;i<to;i++)

#define loopr(i,from,to) for(int i=from;i>=to;i--)

#define pb push_back

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> P;

const int INF=0x3f3f3f3f;



const int maxn=1000000+5;

int pr[maxn];

bool is_pr[maxn];



int sieve(int n){

    int p=0;

    loop(i,0,n+1) is_pr[i]=true;

    is_pr[0]=is_pr[1]=false;

    loop(i,2,n+1){

        if(is_pr[i]){

            pr[p++]=i;

            for(int j=2*i;j<=n;j+=i)

                is_pr[j]=false;

        }

    }

    return p;

}



int main()

{

    int n;

    while(cin>>n)

        cout<<sieve(n)<<endl;

}
// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <string>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <vector>

#include <queue>

using namespace std;

#define MAX 1000000

#define LMT 1000

unsigned flag[MAX>>6];

int primes[6000000];//5761455

#define ifc(n) (flag[n>>6]&(1<<((n>>1)&31)))

#define isc(n) (flag[n>>6]|=(1<<((n>>1)&31)))



int sieve()

{

    unsigned i, j, k;

    for(i=3; i<LMT; i+=2)

        if(!ifc(i))

            for(j=i*i, k=i<<1; j<MAX; j+=k)

                isc(j);

    return 0;

}



int main()

{

    sieve();

    unsigned int i,L;

    int k=1, count;

    primes[0]=2;

    while(scanf("%d", &L)==1)

    {

        count=1;

        for( i=3; i<=L; i+=2)

        {

            if(ifc(i)==0)

                count++;

        }

        if(L>1)

            printf("%d\n", count);

        else printf("0\n");

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.3706495599213597x):
#include<cstdio>

#include<iostream>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<cstdlib>

#include<ctime>

#include<stack>

#include<queue>

#include<set>

#include<map>

#include<vector>

#define mem(name,value) memset(name,value,sizeof(name))

#define loop(i,from,to) for(int i=from;i<to;i++)

#define loopr(i,from,to) for(int i=from;i>=to;i--)

#define pb push_back

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> P;

const int INF=0x3f3f3f3f;



const int maxn=1000000+5;

int pr[maxn];

bool is_pr[maxn];



int sieve(int n){

    int p=0;

    loop(i,0,n+1) is_pr[i]=true;

    is_pr[0]=is_pr[1]=false;

    loop(i,2,n+1){

        if(is_pr[i]){

            pr[p++]=i;

            for(int j=2*i;j<=n;j+=i)

                is_pr[j]=false;

        }

    }

    return p;

}



int main()

{

    int n;

    while(cin>>n)

        cout<<sieve(n)<<endl;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<cmath>

using namespace std;



bool prime[1000000];



int main()

{

    int i,j,k,l,m,n;

    int count;

    while(cin>>n)

    {

        memset(prime,0,sizeof(prime));

        prime[1]=1;

        prime[2]=0;



        count=0;



        for(j=2;j*j<=n;j++)

        {

            if(prime[j]==0)

            {

                for(k=2;k*j<=n;k++)

                {

                   prime[j*k]=1;

                }

            }

        }

        for(i=1;i<=n;i++)

        {

            if(prime[i]==0)

            count++;

        }

        cout << count << endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.2587402153091243x):
#include<cstdio>

#include<iostream>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<cstdlib>

#include<ctime>

#include<stack>

#include<queue>

#include<set>

#include<map>

#include<vector>

#define mem(name,value) memset(name,value,sizeof(name))

#define loop(i,from,to) for(int i=from;i<to;i++)

#define loopr(i,from,to) for(int i=from;i>=to;i--)

#define pb push_back

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> P;

const int INF=0x3f3f3f3f;



const int maxn=1000000+5;

int pr[maxn];

bool is_pr[maxn];



int sieve(int n){

    int p=0;

    loop(i,0,n+1) is_pr[i]=true;

    is_pr[0]=is_pr[1]=false;

    loop(i,2,n+1){

        if(is_pr[i]){

            pr[p++]=i;

            for(int j=2*i;j<=n;j+=i)

                is_pr[j]=false;

        }

    }

    return p;

}



int main()

{

    int n;

    while(cin>>n)

        cout<<sieve(n)<<endl;

}
// Slower C++ solution:
#include<iostream>

#include<cstring>

#include<math.h>

using namespace std;

const int MAX = 1000000;

int prime(int n)

{

	int ans = 0;

	bool prime[MAX];

	memset(prime, 0, sizeof(prime));

	for (int i = 2; i < n;i++)  

	{ 

		for (int j = 2; j <= n / i; j++)

		{

			if (i*j <= n)

				prime[i*j] = 1;

		}

	}

	for (int i = 2; i <= n; i++)

	{

		if (!prime[i])

			ans++;

	}

	return ans;

}

int main()

{

	int n, m = 0;

	while (cin >> n&&m<30)

	{

		cout << prime(n) << endl;

		m++;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.27352917580049x):
#include<cstdio>

#include<iostream>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<cstdlib>

#include<ctime>

#include<stack>

#include<queue>

#include<set>

#include<map>

#include<vector>

#define mem(name,value) memset(name,value,sizeof(name))

#define loop(i,from,to) for(int i=from;i<to;i++)

#define loopr(i,from,to) for(int i=from;i>=to;i--)

#define pb push_back

using namespace std;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> P;

const int INF=0x3f3f3f3f;



const int maxn=1000000+5;

int pr[maxn];

bool is_pr[maxn];



int sieve(int n){

    int p=0;

    loop(i,0,n+1) is_pr[i]=true;

    is_pr[0]=is_pr[1]=false;

    loop(i,2,n+1){

        if(is_pr[i]){

            pr[p++]=i;

            for(int j=2*i;j<=n;j+=i)

                is_pr[j]=false;

        }

    }

    return p;

}



int main()

{

    int n;

    while(cin>>n)

        cout<<sieve(n)<<endl;

}
// Slower C++ solution:
#include<stdio.h>

#include<math.h>

bool flag[1000000];

int main(void)

{

	long long i,j,p,n,count;

	p = (long long)sqrt(1000000.0);

	for(i = 3; i <= p; i = i + 2)

	{

		if(flag[i] == false)

		{

			for(j = i * i; j <= 1000000; j = j + 2 * i)

			{

				flag[j] = true;

				

			}

		}

	}

		

	while((scanf("%lld",&n)) != EOF)

	{

		

		if(n == 1 || n == 0)

			count = 0;

		else

		{

			count = 1;

			for(i = 3; i <= n; i = i + 2)

			{

				if(flag[i] == false)

					count++;

			}

		}

		printf("%lld\n",count);

	}

	



		

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 3.466636446253425x):
//Author- Simanta Deb Turja

//Team- AUST_HoyeJabe



#include<bits/stdc++.h>

#define pi acos(-1)



typedef unsigned long long ull;

typedef unsigned long ul;

typedef long long ll;

//typedef push_back pb;





using namespace std;



int SieveOfEratosthenes(int n)

{



    bool prime[n+1];

    ull count = 0;

    memset(prime, true, sizeof(prime));



    for (int p=2; p*p<=n; p++)

    {



        if (prime[p] == true)

        {



            for (int i=p*2; i<=n; i += p)

                prime[i] = false;

        }

    }





    for (int p=2; p<=n; p++)

       if (prime[p])

          count++;

 return count;

}



int main()

{

    int n;

    while(cin>>n){

        cout<<SieveOfEratosthenes(n)<<endl;

    }





    return 0;

}
// Slower C++ solution:
#include <iostream>

#include <cstdio>

#include <string>

#include <cstring>

#include <cmath>

#include <algorithm>

#include <vector>

#include <queue>

using namespace std;

#define MAX 1000000

#define LMT 1000

unsigned flag[MAX>>6];

int primes[6000000];//5761455

#define ifc(n) (flag[n>>6]&(1<<((n>>1)&31)))

#define isc(n) (flag[n>>6]|=(1<<((n>>1)&31)))



int sieve()

{

    unsigned i, j, k;

    for(i=3; i<LMT; i+=2)

        if(!ifc(i))

            for(j=i*i, k=i<<1; j<MAX; j+=k)

                isc(j);

    return 0;

}



int main()

{

    sieve();

    unsigned int i,L;

    int k=1, count;

    primes[0]=2;

    while(scanf("%d", &L)==1)

    {

        count=1;

        for( i=3; i<=L; i+=2)

        {

            if(ifc(i)==0)

                count++;

        }

        if(L>1)

            printf("%d\n", count);

        else printf("0\n");

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.369687523672402x):
//Author- Simanta Deb Turja

//Team- AUST_HoyeJabe



#include<bits/stdc++.h>

#define pi acos(-1)



typedef unsigned long long ull;

typedef unsigned long ul;

typedef long long ll;

//typedef push_back pb;





using namespace std;



int SieveOfEratosthenes(int n)

{



    bool prime[n+1];

    ull count = 0;

    memset(prime, true, sizeof(prime));



    for (int p=2; p*p<=n; p++)

    {



        if (prime[p] == true)

        {



            for (int i=p*2; i<=n; i += p)

                prime[i] = false;

        }

    }





    for (int p=2; p<=n; p++)

       if (prime[p])

          count++;

 return count;

}



int main()

{

    int n;

    while(cin>>n){

        cout<<SieveOfEratosthenes(n)<<endl;

    }





    return 0;

}