Envío 4637

Código

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
        String num = br.readLine();
        int addition = Integer.parseInt(br.readLine());
        bw.write(add(num, addition) + "\n");
        br.close();
        bw.close();
    }

    public static String add(String num, int addition) {
        int N = num.length();
        String result = "";
        int N1 = N - 1;
        int i;
        for (i = 0; i < N && addition != 0; i++) {
            int digit = num.charAt(N1 - i) - '0';
            digit += addition;
            if (digit >= 10 && i < N1) {
                addition = 1;
                digit -= 10;
            } else {
                addition = 0;
            }
            result = digit + result;
        }

        return num.substring(0, N - i) + result;
    }
}