You are a helpful assistant. The assistant first thinks about the reasoning process in the mind and then provides the user with the answer. The reasoning process and answer must be formatted exactly as follows:
<think>
[your reasoning process here]
</think>
<answer>
[your answer here]
</answer>
You can choose to imitate the reasoning process of relevant algorithms or explore an appropriate solution on your own. DO NOT use code, and remember to focus on the logical flow.
system
You are required to solve the Travelling Salesman Problem for an undirected flight route network. Your objective is to determine the shortest possible route that visits each of the listed airports exactly once and returns to the starting point.

**Problem to Solve**

- Airports to visit: ELM, SZZ, WRL, EBU, WNP, GUA, GUC, GSE, IMF
- Travel distances (in kilometers) between each pair of airports:
ELM to GUA: 3501
ELM to WNP: 14057
ELM to IMF: 13910
ELM to EBU: 6928
ELM to GSE: 6607
ELM to SZZ: 6935
ELM to WRL: 2881
ELM to GUC: 2577
SZZ to GUA: 9796
SZZ to WNP: 10118
SZZ to IMF: 7504
SZZ to EBU: 2577
SZZ to GSE: 1286
SZZ to WRL: 8682
SZZ to GUC: 8378
WRL to GUA: 3717
WRL to WNP: 13154
WRL to IMF: 14959
WRL to EBU: 9451
WRL to GSE: 8604
WRL to GUC: 792
EBU to GUA: 9743
EBU to WNP: 11494
EBU to IMF: 8351
EBU to GSE: 2550
EBU to GUC: 9147
WNP to GUA: 15534
WNP to IMF: 4404
WNP to GSE: 10196
WNP to GUC: 12850
GUA to IMF: 16792
GUA to GSE: 9497
GUA to GUC: 3413
GUC to IMF: 14655
GUC to GSE: 8300
GSE to IMF: 7918
Please calculate the shortest tour and format your answer as follows: [Airport A, Airport B, Airport C, ..., Airport A]
user
{"directed": false, "multigraph": false, "graph": {}, "nodes": [{"name": "ELM", "id": 0}, {"name": "SZZ", "id": 1}, {"name": "WRL", "id": 2}, {"name": "EBU", "id": 3}, {"name": "WNP", "id": 4}, {"name": "GUA", "id": 5}, {"name": "GUC", "id": 6}, {"name": "GSE", "id": 7}, {"name": "IMF", "id": 8}], "links": [{"weight": 3501, "source": 0, "target": 5}, {"weight": 14057, "source": 0, "target": 4}, {"weight": 13910, "source": 0, "target": 8}, {"weight": 6928, "source": 0, "target": 3}, {"weight": 6607, "source": 0, "target": 7}, {"weight": 6935, "source": 0, "target": 1}, {"weight": 2881, "source": 0, "target": 2}, {"weight": 2577, "source": 0, "target": 6}, {"weight": 9796, "source": 1, "target": 5}, {"weight": 10118, "source": 1, "target": 4}, {"weight": 7504, "source": 1, "target": 8}, {"weight": 2577, "source": 1, "target": 3}, {"weight": 1286, "source": 1, "target": 7}, {"weight": 8682, "source": 1, "target": 2}, {"weight": 8378, "source": 1, "target": 6}, {"weight": 3717, "source": 2, "target": 5}, {"weight": 13154, "source": 2, "target": 4}, {"weight": 14959, "source": 2, "target": 8}, {"weight": 9451, "source": 2, "target": 3}, {"weight": 8604, "source": 2, "target": 7}, {"weight": 792, "source": 2, "target": 6}, {"weight": 9743, "source": 3, "target": 5}, {"weight": 11494, "source": 3, "target": 4}, {"weight": 8351, "source": 3, "target": 8}, {"weight": 2550, "source": 3, "target": 7}, {"weight": 9147, "source": 3, "target": 6}, {"weight": 15534, "source": 4, "target": 5}, {"weight": 4404, "source": 4, "target": 8}, {"weight": 10196, "source": 4, "target": 7}, {"weight": 12850, "source": 4, "target": 6}, {"weight": 16792, "source": 5, "target": 8}, {"weight": 9497, "source": 5, "target": 7}, {"weight": 3413, "source": 5, "target": 6}, {"weight": 14655, "source": 6, "target": 8}, {"weight": 8300, "source": 6, "target": 7}, {"weight": 7918, "source": 7, "target": 8}]}
You are required to solve the Travelling Salesman Problem for an undirected flight route network. Your objective is to determine the shortest possible route that visits each of the listed airports exactly once and returns to the starting point.

**Problem to Solve**

- Airports to visit: ELM, SZZ, WRL, EBU, WNP, GUA, GUC, GSE, IMF
- Travel distances (in kilometers) between each pair of airports:
ELM to GUA: 3501
ELM to WNP: 14057
ELM to IMF: 13910
ELM to EBU: 6928
ELM to GSE: 6607
ELM to SZZ: 6935
ELM to WRL: 2881
ELM to GUC: 2577
SZZ to GUA: 9796
SZZ to WNP: 10118
SZZ to IMF: 7504
SZZ to EBU: 2577
SZZ to GSE: 1286
SZZ to WRL: 8682
SZZ to GUC: 8378
WRL to GUA: 3717
WRL to WNP: 13154
WRL to IMF: 14959
WRL to EBU: 9451
WRL to GSE: 8604
WRL to GUC: 792
EBU to GUA: 9743
EBU to WNP: 11494
EBU to IMF: 8351
EBU to GSE: 2550
EBU to GUC: 9147
WNP to GUA: 15534
WNP to IMF: 4404
WNP to GSE: 10196
WNP to GUC: 12850
GUA to IMF: 16792
GUA to GSE: 9497
GUA to GUC: 3413
GUC to IMF: 14655
GUC to GSE: 8300
GSE to IMF: 7918
Please calculate the shortest tour and format your answer as follows: [Airport A, Airport B, Airport C, ..., Airport A]
test