import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
import java.util.List;
import java.util.Arrays;
import java.util.ArrayList;
public class Main {
    //Program start
    
    //Program end

    @Test
public void test1() {
    assertEquals("3", digitSum("11111222223", 3));
}
@Test
public void test2() {
    assertEquals("3", digitSum("00000000", 3));
}

}