import java.io.*;

public class No446{
    public static void main(String[] args) throws IOException{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String a = br.readLine();
        String b = br.readLine();
        char[] A = a.toCharArray();
        char[] B = b.toCharArray();
        if(check(a, A) && check(b, B))  System.out.println("OK");
        else  System.out.println("NG");
    }
        
    public static boolean check(String a, char[] A){
        boolean c = false;
        int count = 0;
        for(int i=0; i < A.length; i++)
            if(Character.isDigit(A[i]))  count++;
        if(count == A.length){
           int num = Integer.parseInt(a);
           if(num != 0 && a.startsWith("0"))  return c;
           else if(num == 0 && a.startsWith("00")) return c;
           else if(0 <= num && num <= 12345 ) c = true;
        }
        return c;
    }
}