changes

sink/Makefile

@@ -13,6 +13,7 @@ LDFLAGS =
 TARGET = sink20169
 
 all: $(BUILD_DIR)/$(TARGET)
+
 OBJECTS = $(addprefix $(BUILD_DIR)/,$(notdir $(C_SOURCES:.c=.o)))
 vpath %.c $(sort $(dir $(C_SOURCES)))
 
@@ -21,3 +22,10 @@ $(BUILD_DIR)/%.o: %.c Makefile | $(BUILD_DIR)
 
 $(BUILD_DIR)/$(TARGET): $(OBJECTS) Makefile
 	$(CC) $(OBJECTS) $(LDFLAGS) -o $@
+
+$(BUILD_DIR):
+	mkdir $@
+
+.phony: clean
+clean:
+	-rm -rf $(BUILD_DIR)