Cross Bridges and Conquer

As Sheldor the conqueror, you're supposed to conquer the kingdom of Wonder-blunder-berg , which happens to be a collection of cities connected with roads. This is the Adjacency List of the road network of WonderBlunderBerg showing which city has a direct road to which other city.

For Sheldor the conqueror to walk from city 1 to city 20, how many minimum bridges would he have to cross?

Definitions :

• A component is a maximal set of cities such that there is a walk between any two cities of the set.
• A bridge is a road which when removed increases the number of components.
• The original kingdom is connected , meaning that there is only one component.

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Try Also: Can you cut the bridges and conquer ?