1) Saudi Arabia


 You have to live in this country for atleast 20 years and usually muslim gets the citizenship or you have to convert to Islam

2) Bhutan


Your both parents should be from Bhutan or if only one parent is from Bhutan you have to live here for 15 years

3) Liechtenstein


You have to live here for 30 years and if you marry a person from Liechtenstein you have to live here 25 years 

4) North Korea


Citizenship is only possible if you have any blood relation here

5) Vatican City


It is the world's smallest country and only 450 people lives here you can get citizenship if you work for the church