def test_simple_non_bipartite_graph(self):
g = Graph(v=['A', 'B', 'C'], e=[('A', ['B']), ('B', ['C']), ('C', ['A'])])
self.assertFalse(g.is_bipartite())
import sys
from kihon.graphs import Graph
if __name__ == '__main__':
cases = int(sys.stdin.readline())
for i in range(cases):
edge_number = int(sys.stdin.readline())
g = Graph(kind=Graph.UNDIRECTED)
for edge in range(edge_number):
g.add_edge(*sys.stdin.readline().split())
sol = "yes" if g.is_bipartite() else "no"
#print(g)
print("Case #%d: %s" % (i + 1, sol))
def test_simple_bipartite_graph(self):
g = Graph(v=['A', 'B'], e=[('A', ['B'])])
self.assertTrue(g.is_bipartite())
