To the left you see a flow network with source labeled , sink , and four additional nodes. The flow and capacity is denoted formula_1. Notice how the network upholds skew symmetry, capacity constraints and flow conservation. The total amount of flow from to is 5, which can be easily seen from the fact that the total outgoing flow from is 5, which is also the incoming flow to . We know that no flow appears or disappears in any of the other nodes.