#include <iostream>
#include <list>
#include <algorithm>
using namespace std;
 
 bool compare(string a, string b) {
        cout << a.front() << "  " << b.front() << endl;
        return(a.front() == b.front());
    }
    void Fifth_task(list <string>& lst) {
        list <string> ::iterator it;
        lst.sort();
        lst.unique(compare);
        for (it = lst.begin(); it != lst.end(); ++it) {
            cout << *it << endl;
        }
    }
 
 
    int main(){
    list <string> first;
    first.push_back("Hello");
    first.push_back("Johnny");
    first.push_back("Hello");
    first.push_back("Ildar");
    Fifth_task(first);
    return 0;
    }

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