04. Short Words

#include <iostream>
#include <string>
#include <utility>
#include <sstream>
#include <set>
using namespace std;

string &lower_str(string &str)
{
for( string::iterator i = str.begin(); i != str.end(); i++)
*i = tolower(*i);

return str;
}

int main()
{
 string str;
getline(cin, str);
istringstream istr(lower_str(str));

string word;
set<string> words;

while(istr >> word)
words.insert(word);

bool first = true;

for(set<string>::iterator i = words.begin(); i != words.end(); i++)
{
if(i->length() < 5)
{
if(first)
first = false;
else
cout << ", ";

cout << *i;
}
}
cout << endl;
}