// editor1
#include<stdio.h>
#include<string.h>
#include<ctype.h>

int main(){
    char s1[101],s2[101];
    int i,v=1;
    scanf("%s", s1);
    scanf("%s", s2);
    for (i=0;s1[i]!='\0';i++){
        if(isalpha(s1[i])){
            v=0;
            break;
        }
    }
    for (i=0;s1[i]!='\0';i++){
        if(isalpha(s1[i])){
            v=0;
            break;
        }
    }
    for (i=0;s2[i]!='\0';i++){
        if(isalpha(s2[i])){
            v=0;
            break;
        }
    }
    if(v){
        strcast(s1, s2);
        printf("%s",s1);
    }else{
        printf("Invalid Input\n");
    }
    return 0;
}