#include <unistd.h>
#include <stdio.h>

void	ft_putstr(char *str)
{
	int	i;

	i = 0;
	while (str[i])
	{
		write(1,&str[i],1);
		i++;
	}
}

int		ft_atoi(char *str)
{
	int i;
	int	is_neg;
	int	res;

	i = 0;
	is_neg = 0;
	res = 0;
	if (!str)
		return (0);
	while (str[i] == '\t' || str[i] == '\n' || str[i] == '\r' || str[i] == '\v' || str[i] == '\f')
		i++;
	if (str[i] == '+' || str[i] == '-')
	{
		if (str[i] == '-')
			is_neg = 1;
	i++;
	}
	while (str[i] >= '0' && str[i] <= '9')
	{
		res = (res * 10) + (str[i] - '0');
		i++;
	}
	return (is_neg ? -res : res);
}

void	ft_putnbr(int nb)
{
	char c;

	if (nb == -2147483648)
		ft_putstr("-2147483648");
	if (nb < 0)
	{
		nb = -nb;
		write(1, "-", 1);
	}
	if (nb < 10)
	{
		c = nb + '0';
		write(1, &c, 1);
	}
	else
	{
		ft_putnbr(nb / 10);
		ft_putnbr(nb % 10);
	}
}

int		is_prime(int nb)
{
	int	i;

	i = 2;
	if (nb < 0)
		return (0);
	while (i <= (nb / 2))
	{
		if (!(nb % i))
			return (0);
		else
			i++;
	}
	return (1);
}

int		main(int ac, char *av[])
{
	int	sum;
	int nb;

	sum = 0;
	nb = ft_atoi(av[1]);
	if (ac == 2 && nb > 0)
	{
		while (nb > 0)
		{
			if (is_prime(nb))
				sum += nb;
			nb--;
		}
		ft_putnbr(sum);
	}
	else
		write (1,"0",1);
	write(1, "\n", 1);
	return (0);
}