Read the following materials: in 1750, Euler listed some properties of polyhedron in his letter to Goldbach, one of which is: if V, e and F are used to represent the vertex number, edge number and face number of convex polyhedron, then V-E + F = 2. This discovery is the famous Euler theorem. According to the materials read, we complete: if the face number of a polyhedron is 12 and the edge number is 30, then the vertex number of a polyhedron is 12 The number of points is______ .

Read the following materials: in 1750, Euler listed some properties of polyhedron in his letter to Goldbach, one of which is: if V, e and F are used to represent the vertex number, edge number and face number of convex polyhedron, then V-E + F = 2. This discovery is the famous Euler theorem. According to the materials read, we complete: if the face number of a polyhedron is 12 and the edge number is 30, then the vertex number of a polyhedron is 12 The number of points is______ .

The answer is: 20