Sieve of Eratosthenes- C++

 #include<bits/stdc++.h>

using namespace std;

void sieve(long long n)

{

bool prime[n+1];

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

long long i,p=0,j;

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

{

if(prime[i])

{

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

{

prime[j]=false;

}

}

}

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

{

if(prime[i])

{

cout<<i<<" ";

p++;

}

}

cout<<endl<<p<<endl;

}

int main()

{

ios_base :: sync_with_stdio(0);cin.tie(0);cout.tie(0);

//freopen("input.txt","r",stdin);

long long n;

cin>>n;

sieve(n);

return 0;

}