n=int(input()) for i in range(n): a,b=input().split() #和的反转 he1=int(a)+int(b) fan1=str(he1)[::-1] #反转的和 a=a[::-1] b=b[::-1] he2=int(a)+int(b) fan2=str(he2) #判断 if fan1==fan2: print(he1) else: print("NO")