first_numbers.ptuc

program calculate;
	var limit, number, counter: integer;

	function prime(n: integer): boolean;
		var
			i : integer;
			isPrime : boolean;

	begin
		if n < 0 then
			result := prime(-n);
	
		else if n = 2 then
			result:=true;
		else if n mod 2 = 0 then
			result:=false;

		
		else

			begin
				i := 3;
				isPrime := true;
				while isPrime and (i < n div 2) do 
		
					begin
						isPrime := n mod i <> 0;
						i := i+2;
					end

					result := isPrime;



			end

		return
	end;

begin
	limit := readInteger();
	counter := 0;
	number := 2;

	while number <= limit do 
	begin
		if prime(number) then 
		begin
			counter := counter + 1;
			writeInteger(number);
			
		end

		number := number + 1;
	end

	
	writeInteger(counter);
	
end

.