POJ 2135 - Farm Tour
Problem : Given a graph, find two edge-independent path and make the total distance minimum.
Solution : For each edge, has capacity 1 and cost dis(e). Link source to s with capacity 2, cost 0. Link t to sink with capacity 2, cost 0.

POJ 3422 - Kaka's Matrix Travels
Problem : Raw Maximum Cost Maximum FLow.