I don't know if this question has been asked before, but I've searched for previous posts with the same question and didn't find any - though if I missed such one, I'd appreciate the reference.
Let $G=(V,E)$ be a flow network with source-$s$, sink-$t$ and integral positive capacities. We say that flow $f$ is even if $f(u,v)$ is an even number for all $u,v\in V$. Describe an algorithm, as efficient as possible, that finds maximum flow among all even flows.
I'm familiar with The Ford-Fulkerson method, Edmonds Karp's implementation and Dinic's algorithm for finding maximal flow. I guess there is some manipulation required to be done on the network but can't see it.