private void Box3_TextChanged(object sender, EventArgs e)
{
int[,] arr = mapTableToArray(); CCC = new CheckCorrectCell(arr);
if (CCC.checkCorrectCell9x9(0, 2) &&
Box3.Text != ""){
Box3.BackColor = Color.Red;} else
Box3.BackColor = Color.White;
congratulations9x9();
}