feat(01-totwodigits): Добавлено задание

labs/01-totwodigits/app/src/main/java/ru/mrqiz/totwodigits/App.java

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+package ru.mrqiz.twodigits;
+
+import java.util.Scanner;
+
+public class App {
+  private static int convertTo2Digit(int n) {
+    int res = 0;
+    n = Math.abs(n);
+    while (n > 0) {
+      res += n % 10;
+      n /= 10;
+    }
+    return res;
+  }
+
+  public static void main(String[] args) {
+    Scanner in = new Scanner(System.in);
+    int n = 0;
+    boolean validInput = false;
+
+    while (!validInput) {
+      System.out.print("can i get an int?\n> ");
+      if (in.hasNextInt()) {
+        n = in.nextInt();
+        validInput = true;
+      } else {
+        System.out.println("NaN, wrong.");
+        in.next();
+      }
+    }
+
+    while (Math.abs(n) > 9) {
+      n = convertTo2Digit(n);
+    }
+    System.out.println(n);
+
+  }
+}