//#include<iostream> //#include<cstdio> #include <stdio.h> //using namespace std; int reverse(int x){ //求反序数 int revx=0; while(x!=0){ revx *= 10; revx += x%10; x /= 10; } return revx; } int main(){ int a,b,c;int a1,b1,c1; while(scanf("%d%d",&a,&b)!=EOF){ c=a+b; a1=reverse(a); b1=reverse(b); c1=reverse(c); if(a1+b1==c1)printf("%d\n",c); else printf("NO"); } }