#include <cstdlib>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <string>
using namespace std;
int main() {
string a, b;
while (cin >> a >> b) {
int num1=atoi(a.c_str())+atoi(b.c_str());
reverse(a.begin(),a.end());
reverse(b.begin(),b.end());
int num2=atoi(a.c_str())+atoi(b.c_str());
string str1=to_string(num1);
string str2=to_string(num2);
reverse(str2.begin(),str2.end());
if(str1==str2)
{
cout<<num1<<endl;
}
else {
cout<<"NO"<<endl;
}
}
return 0;
}

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