function Start () {
    var mesh : Mesh = GetComponent(MeshFilter).sharedMesh;
    print(mesh.vertexCount);
}

using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void Start() {
        Mesh mesh = GetComponent<MeshFilter>().sharedMesh;
        print(mesh.vertexCount);
    }
}

import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def Start():
        mesh as Mesh = GetComponent[of MeshFilter]().sharedMesh
        print(mesh.vertexCount)