MathDB

In country there are two capitals (

A

and

B

) and finite number of towns. Some towns (or town with one of capital) connected with roads (one-way). (between every two towns or capital and town there are arbitrary number of roads) such that exist at least one way from

A

B

. Given, that any two ways from

A

B

have at least one common road. Prove, that exist one road, such that all ways from

A

B

pass through this road.

Problem Statement