What can be the **fastest** way to to check the duplicate values in the dictionary and print its key?

Dictionary `MyDict` which is having following values,

Key **Value**

22 **100**

24 **200**

25 **100**

26 **300**

29 **200**

39 **400**

41 **500**

Example: key 22 and 25 have same values and i need to print that 22 and 25 have duplicate values.