#include<stdio.h>
#include<string.h>
int main(){
    char s1[100];
    char s2[100];
    scanf("%s,%s",s1,s2);
    for (int i=0; s1[i] !='\0';i++ {
        if(!isalpha(s1[i])){
            printf("Invalid Input\n");
            return 0;
    }
}
    for (int i=0; s2[i] !='\0';i++ {
        if(!isalpha(s2[i])){
            printf("Invalid Input\n");
            return 0;
        }
    }
    strcat(s1, s2);
    printf("%s\n",s1);
   
    return 0;
}