Put sugar, yeast, flours and salt into bowl. Mix until forms and make well in center. Pour in warm water and mix with spoon until forms a sticky dough. Knead on worktop, using more barley flour, 3 to 4 minutes. Put dough back into bowl and let rise in warm place one hour, covered with clean towel. Knead again 4 to 5 minutes and shape into ball. Put on greased baking sheet and flatten. Cut top with knife, dividing loaf into three. Let rise in warm place. When doubled in size, bake in preheated 400° oven 35 to 40 minutes. Take out of oven and turn upside down on baking sheet to cool.