#include<iostream>
#include<iomanip>
#include<string>
using namespace std;
class Check
{
   public:
    Check()
    {
     string str;
     string st;
    }
     Check( string str, string st)
     {
         for(int i=0;i<str.length();i++)
         {
         if(str.empty())
         {
             cout<<"Invalid input";
             
         }
         if((str[i] >= 'a' && str[i] <= 'z') ||(str[i] >= 'A' && str[i] <= 'Z'))
         {
             continue;
         }
         if(!(str[i]== '0'||str[i]== '1'||str[i]== '2'||str[i]== '3'||str[i]== '4'||str[i]== '5'||str[i]== '6'||
         str[i]== '7'||str[i]== '8'||str[i]== '9'))
         {
             if(str[i] == ' ')
             {
                 i++
             }
             st += str[i];
         }
         else
         {
             cout<<"Invalid input";
             
         }
         }
         cout<<st;
     }
};
int main()
{
    
    string s1;
    string s2 = "";
    getline(cin,s1);
    Check c1(s1, s2);
    return 0;
}