#include <stdio.h>
#include <ctype.h>

int main(){
    char s1[101], s2[101];
    
    scanf("%100s", s1);
    scanf("%100s", s2);
    
    for (int 1 = 0; s1[i] != '\0'; i++){
    if (!isalpha((unsigned char)s1[i])) {
        printf("Inavlid input");
        return 0;
    }
    }    
    for(int i = 0; s2[i] != '\0'; i++) { 
    if (!isalpha((unsigned char)s2[i]))
    {
        printf("Invalid input");
        return 0;
    }
    }    
    printf("%s%s", s1, s2);
    return 0;
}