Java 11
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
public class Main {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringBuilder sb = new StringBuilder();
while(true) {
String str = br.readLine();
int a = str.charAt(0) -48;
int b = str.charAt(2) -48;
if (a == 0 && b == 0) break;
sb.append((a+b)).append('\n');
}
System.out.println(sb);
}
}