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

int main() {
    char  input[] = {"0123456789abcdefABCDEF"};
    char output[] = {"084C2A6E195D3B7F5D3B7F"};
    char str[200]={0}, str2[100];
    scanf("%s %s", str, str2);
    int n1 = strlen(str);
    int n2 = strlen(str2);
    for (int i = n1; i < n1 + n2; i++) {
        str[i] = str2[i - n1];
    }
    int j;
    int len = strlen(str);
 
    for (int k = 0; k <= 1; k++) {
        for (int i = k; i < len; i = i + 2) {
            char target = str[i];
            for (j = i - 2; j >= 0; j = j - 2) {
                if (str[j] > target) {
                    str[j + 2] = str[j];
                } else {
                    break;
                }
            }
            str[j+2] = target;
        }
    }
 

    for(int i = 0;i<len;i++)
    {
        if(isdigit(str[i]) || str[i]>='a'&&str[i]<='f' || str[i]>='A'&&str[i]<='F')
        {
            for(int j = 0;j<22;j++)
            {
                if(str[i] == input[j])
                {
                    str[i] = output[j];
                    break;
                }
            }
        }
    }

    printf("%s",str);

    


}