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 to B.
Given, that any two ways from A to B have at least one common road.
Prove, that exist one road, such that all ways from A to B pass through this road. combinatorics proposedcombinatorics