Coin black sea help [solved]

Found this coin at the coast of black sea byala,anyone know what type of coin it is?

Looks like an extremely corroded and worn down old stotinka coin from the People's Republic of Bulgaria. I can just about make out some of the words on the legend ( Република - Republic )   on the rim and the COA  . What is the diameter ? That will help narrowing down what this used to be .

I used The iphone app,the width is 2 cm

If not 2 ,then 2,50 i think

I blew up one of the pictures on my computer and was able to see  a barely visible 5 on one side of the coin . 

The 5 stotinki has a diameter of 2.2cm , which could easily have been worn down to 2 by the sand and sea .

So you coin is a 5 stotinki in my opinion . The year  I can't tell - sometime between 1962-1990 . If I had to make a guess , I'd say 1974 , simply because those are most numerous .Her is how it looked new , before someone lost it all those years ago 

N#3762

N#841