#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n,a,b,af,bf; cin>>n; while(n--){ cin>>a>>b; int t; t=a; af=0; while(t!=0){ af=af*10+t%10; t/=10; } t=b; bf=0; while(t!=0){ bf=bf*10+t%10; t/=10; } t=a+b; int abf=0; while(t!=0){ abf=abf*10+t%10; t/=10; } if(abf==af+bf) cout<<a+b; else cout<<"NO"; cout<<endl; } return 0; }