import java.util.Scanner ;
 
class Main
{
public static void main(String args[])
{
Scanner scc =new Scanner(System.in);
int nn=scc.nextInt(),i=0;
while((nn--)>0)
{
String s1,s2,s3="";
s1=scc.next();
s2=scc.next();
int l1=s1.length(),l2=s2.length();
for(i=0;i<(int)(l1/l2);i++)
{
	s3+=s2;
}
for(i=0;i<(int)(l1%l2);i++)
{
	s3+=s2.substring(0,(int)(l1%l2));
}
s2="";
for(i=0;i<(int)l1;i++)
{
	char c=(char)((int)s1.charAt(i)+(int)s3.charAt(i));
	if((int)c>122)
	c-=26;
	s2+=c;
}
System.out.println(s2);
}
}
}

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