1	integer function (integer a, integer b, integer c)
2	e_code=-1
3	if (not (isnumber(a) and isnumber(b) and isnumber(c)))
4		write "Invalid argument"
5		e_code=1
6	elseif ((a==0) or (b==0) or (c==0))
7		write "Invalid argument"
8		e_code=2
9	elseif (((a+b)<=c) or ((b+c)<=a) or ((c+a)<=b))
10		write "Not a triangle"
11		e_code=3
12	elseif ((a==b) and (b==c) and (a==c))
13		e_code=0
14		write "Equilateral"
15	elseif ((a==b) or (b==c) or (c==a))
16		e_code=0
17		write "Isosceles"
18	else
19		e_code=0
20		write "Scalene"	
21	endif
22	return(e_code)