#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<set>
#include<sstream>
using namespace std;
int main()
{
    string M;
    set<string> S;
    getline(cin,M,'.');
    istringstream is(M);//自动过滤空格
    string t;
    string a;
    int maxlen=0; 
    while(is>>t)
    {
        if(maxlen<t.size())
        {
            maxlen=t.size();
            a=t.substr(0,t.size());
        }
    }
    //cout<<maxlen<<endl;
    cout<<a<<endl;
    return 0;
}