#include <stdio.h>
#include <ctype.h>
int main() {
    char s1[101],s2[101];
    if (scanf("%s%s,s1,s2") !=2)
return 0;
     for (int i = 0; s1[i] || s2[i]; i++)
          if ((s1[i] && !isalpha(s1[i]))
|| (s2[i] && !isalpha(s2[i])))  {
            print("invalid input\n");
            return 0;
        } 
     print("%s%s\n",s1,s2) ;
     return 0;
}