import pickle
try:
    import _pickle
except ImportError:
    import cPickle as _pickle

N = 2000

graph_vertices = [[] for i in range (N)]

def add_edge(vs, u, v):
  edge = (vs[u], vs[v])
  vs[u].append(edge)
  vs[v].append(edge)

for u in range(N):
  for v in range(20):
    add_edge(graph_vertices, u, (u + v) % N)

try:
    d1 = pickle.dumps(graph_vertices)
except RuntimeError as e:
    print(repr(e))

try:
    d2 = _pickle.dumps(graph_vertices)
except RuntimeError as e:
    print(repr(e))