In a large bowl, sprinkle yeast into 1/2 cup water. Stir in the sugar and let mixture stand until foamy, about 5 minutes. With wooden spoon, beat 3 1/2 cups flour, remaining 1 1/2 cups water, and the olives, rosemary, and salt into yeast mixture until combined. Turn dough out onto lightly floured surface. Knead dough, adding remaining flour as necessary to prevent sticking, until smooth and elastic, about 10 minutes. Wash, dry, and lightly oil mixing bowl. Place dough in oiled bowl, turning to bring oiled side up. Cover with clean cloth. Let dough rise in warm place until it doubles in size, about 1 1/2 hours. Lightly grease 2 baking sheets. Divide dough into quarters; shape each quarter into an 8x3-inch loaf. Place 2 loaves on each greased sheet; cover loosely with clean cloth and let rise in warm place until they double in size, about 40 minutes. Heat oven to 400 degrees. When loaves have doubled, brush tops with olive oil. Bake 25 to 30 minutes or until lightly browned and loaves sound hollow when tapped on top. Cool on wire rack at least 10 minutes before serving.