#include <iostream>
#include <fstream>

using namespace std;

char text[100];
int a, b, c;

int main(void)
{
	ifstream input_file;
	ofstream output_file;

	input_file.open ("adunare.in", fstream::in);
	input_file.getline(text,100);

		a = strtol(text,NULL,10);

	input_file.getline(text,100);

		b = strtol(text,NULL,10);

	input_file.close ();

		c = a + b;

	
	output_file.open ("adunare.out", fstream::out);

	if (c <= 2000000000)
	{
		output_file << c;
	}
	else
	{
		output_file << "error";
	}
	output_file.close();

	return 0;
}