#include<stdio.h>
#include<string.h>
#include<ctype.h>
int isAlphabetic(char str[])
{
    for(int i=0;str[i]!='\0';i++)
    {
        if(!isalpha(str[i]))
        {
            return 0;
        }
    }
    return 0;
}
int main()
{
    char s1[101];
    char s2[101];
    scanf("%s",s1);
    scanf("%s",s2);
    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;
}