标准库问题

下面这个问题这么结束输入。

#include <iostream>

#include <vector>

#include <string>

#include <algorithm>

using namespace std;

int main()

{

vector<string> coll;

copy (istream_iterator <string> (cin),

istream_iterator <string> (),

back_inserter (coll));

sort (coll.begin(), coll.end());

unique_copy (coll.begin(), coll.end(), ostream_iterator <string> (cout, "\n"));

return 0;

}