#include<iostream>
#include<cmath>
#include<bitset>

using namespace std;
int main()
{
	int const max_number(100);
	int const max_test((int)sqrt ((double)max_number));
	bitset<max_number+1> numbers;//101个0
	numbers.set();//101个1
	numbers[1]=0;
	for(int i(1);i!=max_test;++i)
	{
		if(numbers[i])
		{
			for(int j=i*i;j<max_number+1;j+=i)
			{
				numbers[j]=0;
			}
		}
	}
	cout<<"the number of primes less than"<<max_number+1
		<<"is"<<numbers.count()<<endl;
	for(int i(1);i!=max_number+1;++i)
	{
		if(numbers[i])
			cout<<i<<".";
	}
	return 0;
}