#include <math.h>
#include <stdio.h>

int reverse(int x) {
    int reversed = 0;
    while (x != 0) {
        int c =  x % 10;
        reversed = reversed * 10 + c ;
        x /= 10;
    }
    return reversed;
}

void isequal(int x, int y) {
    int sum1 = x + y;
    int x1=reverse(x);
    int y1=reverse(y);
    int sum2 =x1+y1;
    if (sum2 == reverse(sum1)) {
        printf("%d\n", sum1);
    } else{
        printf("NO\n");
    }
}

int main() {
    int a, b;
    while (scanf("%d %d", &a, &b) != EOF) {
        isequal(a, b);
    }
    return 0;
}