输入三角形的三条边a，b，c，判断它们能否构成三角形。若能构成三角形，指出是何种三角形（等腰三角形、等边三角形、直角三角形、等腰直角三角形、一般三角形）。(Input the three sides of the triangle a, B, C to decide whether they can form a triangle. If we can form triangles, we point out what triangles (isosceles triangle, equilateral triangles, right angled triangles, isosceles right angled triangles, general triangles).)