<｜begin▁of▁sentence｜>### Instruction:
Given an undirected graph with edge set [(1, 2), (1, 3), (2, 3), (3, 4)], create an auxiliary graph for flow-based node connectivity and find the minimum number of nodes that must be removed to disconnect nodes 1 and 4 using this auxiliary graph.
### Response:
import networkx as nx

# Create an undirected graph G
G = nx.Graph()
G.add_edges_from([(1, 2), (1, 3), (2, 3), (3, 4)])

# Build the auxiliary graph for node connectivity
H = nx.build_auxiliary_node_connectivity(G)

# Print information about the auxiliary graph
print('Number of nodes in auxiliary graph:', H.number_of_nodes())
print('Number of edges in auxiliary graph:', H.number_of_edges())
print('Mapping of nodes from G to H:', H.graph['mapping'])

# Example to demonstrate the use of the auxiliary graph
cut_value, partition = nx.minimum_node_cut(H, H.graph['mapping'][1+'A'], H.graph['mapping'][4+'B'])
# Convert partition to original node labels
original_nodes_partition = {G.nodes[orig] for orig in partition if orig[-1] == 'A'}

print('Minimum node cut for the original graph:', original_nodes_partition)
print('Cut value:', cut_value)
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