#include<iostream>
using namespace std;
int main()
{
    string s;
    getline(cin,s);
    bool invalid=false;
    for(int i=0;I<s.legth();i++)
    {
        if(s[i]=='-')
        {
            invalid=true;
            break;
        }
    }
    if(invalid0)
    {
        cout<<"Invalid input";
        return 0;
    }
    string cleaned="";
    for(int i=0;i<s.legth();i++)
    {
        if((s[i]>='a'&& s[i]<='z')||(s[i]>='A'&&s[i]<='Z')||(s[i]>='0'&&s[i]<='9'))
        {
            cleaned+=s[i];
        }
    }
    cout<<cleaned;
    return 0;
}