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Given a list of airline tickets represented by pairs of departure and arrival airports `[from, to]`

, reconstruct the itinerary in order. All of the tickets belong to a man who departs from `JFK`

. Thus, the itinerary must begin with `JFK`

.

**Note:**

- If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order when read as a single string. For example, the itinerary
`["JFK", "LGA"]`

has a smaller lexical order than`["JFK", "LGB"]`

. - All airports are represented by three capital letters (IATA code).
- You may assume all tickets form at least one valid itinerary.

**Example 1:**

`tickets`

= `[["MUC", "LHR"], ["JFK", "MUC"], ["SFO", "SJC"], ["LHR", "SFO"]]`

Return `["JFK", "MUC", "LHR", "SFO", "SJC"]`

.

**Example 2:**

`tickets`

= `[["JFK","SFO"],["JFK","ATL"],["SFO","ATL"],["ATL","JFK"],["ATL","SFO"]]`

Return `["JFK","ATL","JFK","SFO","ATL","SFO"]`

.

Another possible reconstruction is `["JFK","SFO","ATL","JFK","ATL","SFO"]`

. But it is larger in lexical order.

**Credits:**

Special thanks to @dietpepsi for adding this problem and creating all test cases.

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