不用#include<string.h>库

#include<stdio.h>

int main(){
	int n;
	scanf("%d",&n);
	while(n--){
		char a[40] = {0};
		char b[40] = {0};
		scanf("%s %s",a,b);
		for(int i=39;i>=0;i--){
			if(b[i]>='a'&&b[i]<='z'){
				printf("%c",b[i]);
			}
		}
		for(int i=39;i>=0;i--){
			if(a[i]>='a'&&a[i]<='z'){
				printf("%c",a[i]);
			}
		}
		printf("\n");
	} 
	
	return 0;
}