  In 1975, Erd\H{o}s asked the following question: what is the smallest
function $f(n)$ for which all graphs with $n$ vertices and $f(n)$ edges contain
two edge-disjoint cycles $C_1$ and $C_2$, such that the vertex set of $C_2$ is
a subset of the vertex set of $C_1$ and their cyclic orderings of the vertices
respect each other? We prove the optimal linear bound $f(n)=O(n)$ using
sublinear expanders.
