import java.util.*;
class M{
  static String c(String z, String y){
    int i = 0,
        l = y.length();
    if(z.length() > l){
      return c(y, z);
    }
    List x = new ArrayList();
    for(; i < l; x.add(y.toCharArray()[i++]));
    for(Object q : z.toCharArray()){
      x.remove(q);
    }
    String r = "";
    for(i = 0; i < (x.size()); r += x.get(i++));
    return z+"_"+r;
  }

  public static void main(String[] a){
    System.out.println(c("sale", "salinewater"));
    System.out.println(c("jostling", "juggle"));
    System.out.println(c("juggle", "juggler"));
  }
}