eof질문있습니다.

#include <iostream>
#include <vector>
#include <iterator>
#include <algorithm>
#include <string>
using namespace std;
 
int main()
{
    vector<string> add;
    copy(istream_iterator<string>{cin}, istream_iterator<string>{}, back_inserter(add));
    cin.clear();
    if(cin.eof())
    {
        cout<<"EOF"<<endl;
        exit(0);
    }
    copy(istream_iterator<string>{cin}, istream_iterator<string>{}, back_inserter(add));
 
    copy(begin(add), end(add), ostream_iterator<string>{cout," "});
    return 0;
}