#include<stdio.h>
#include<ctype.h>
#include<string.h>
int isAlphabetic(char str[])
{
    for(int i = 0;str[i]!='\0';i++)
    {
        if(!isalpha((unsigned char)str[i]))
        {
            return 0;
        }
    }
     return 1;
}
int main()
{
    char s1[101],s2[101];
    fgets(s1,sizeof(s1),stdin);
    fgets(s2,sizeof(s2),stdin);
    s1[strcspn(s1,'\n')]='\0';   
      s2[strcspn(s2,'\n')]='\0';
      if(isAlphabetic(s1) || isAlphabetic(s2)){
          printf("%s%s",s1,s2);
      }
      else 
      {
          
         printf("Invalid input");
      }

    return 0;
}