02. Odd Occurrences

#include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <map>

using namespace std;

int main() {
    string line, word;
    getline(cin, line);

    istringstream ss(line);

    vector<pair<string, int>> words;

    while (ss >> word) {
        for (int i = 0; i < word.length(); i++) {
            word[i] = tolower(word[i]);
        }

        bool isword = false;

        for (int i = 0; i < words.size(); ++i) {
            if (words[i].first == word) {
                words[i].second++;
                isword = true;
                break;
            }
        }

        if (!isword) {
            words.push_back(make_pair(word, 1));
        }
    }

    vector<string> output;

    for (int i = 0; i < words.size(); i++) {
        if (words[i].second % 2 == 1) {
            output.push_back(words[i].first);
        }
    }

    for (int i = 0; i < output.size(); i++) {
        cout << output[i];
        if (i < output.size() - 1) {
            cout << ", ";
        }
    }

    cout << endl;
    return 0;
}