Python :Non-UTF-8 code starting with '\xe8' in file

Question

I'm a super beginner to python, but I think that if I won't resolve this question, I can't go on with clear mind.I was trying to wright a script with if, elif and else. But there is always the same error occuring.I also search trough web but I didn't get a solution. THANK YOU FOR HELPING!!

ERROR:

File "C:/progetti/main.py", line 5
SyntaxError: Non-UTF-8 code starting with '\xe8' in file C:/progetti/main.py on line 5, but no encoding declared; see http://python.org/dev/peps/pep-0263/ for details


SCRIPT: 
x = 5
y = 8

if x > y:
    print("x è maggiore di y")
elif x < y:
    print("x è minore di y")
else:
    print("sono uguali")

I couldn't fix the error. THANKS