C++ :

#include <string>
#include <iostream>
using namespace std;
int Get(string, char);
int main()
{
	int n, i, j, index;
	bool exist, proper;
	string s[100], temp;
	cin >> n;
	for (i = index = 0; i < n; i++)
	{
		exist = false;
		proper = false;
		cin >> temp;
		for (j = 0; j < index; j++)
		{
			if (s[j] == temp)
			{
				exist = true;
				break;
			}
		}
		if (!exist)
		{
			if (Get(temp, '@') == 1 && Get(temp, '.') == 1
				&& temp.find('@') < temp.find('.'))
				proper = true;
		}
		if (!exist && proper)
		{
			s[index] = temp;
			index++;
		}
	}
	for (i = 0; i < index; i++)
		cout << s[i] << endl;
	return 0;
}
int Get(string s, char a)
{
	int sum = 0, i = 0, l = s.size();
	for (; i < l; i++)
	{
		if (s[i] == a)
			sum++;
	}
	return sum;
}