Wash the rice and boil for 10 minutes. Add 3 ½ cups of milk and let simmer for 15 minutes, stir often. Add the sugar to the mixture. In a small bowl dissolve the corn flour with the remaining milk and add to the pot. Boil the ryzogalo (rice pudding) for 10-15 minutes, stirring continuously until it thickens. Remove from heat, add the vanilla and stir.