Second answer

07/g.py

@@ -86,5 +86,16 @@ for i in dirs.values():
     if dirsize <= 100000:
         tot += dirsize
 
-
 print(tot)
+
+usedspace = dirs['/'].size()
+freespace = 70000000 - usedspace
+candidates = []
+
+for i in dirs.values():
+    dirsize = i.size()
+    if (freespace + dirsize) > 30000000:
+        candidates.append(dirsize)
+
+candidates.sort()
+print(candidates[0])