#include <iostream>
#include <string>
#include <list>
 
int main()
{
        std::list<std::string> l;
        std::string str;
        do {
                std::cin >> str;
                if (str[str.length()-1] == '.') {
                        std::string str2 = str.substr(0, str.length()-1);
                        l.push_back(str2);
                } else {
                        l.push_back(str);
                }
        } while (str[str.length()-1] != '.');
 
        l.sort([](std::string &lhs, std::string &rhs)
                {
                        return (lhs.length() > rhs.length()) ? true : false;
                });
 
        // 輸出最長單字(在最前面)
        std::cout << std::endl << l.front() << std::endl;
 
        return 0;
}

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I am a normal ptt user like everybody.