Question: Not Alone, is Zhang Liyin's which number overall single, Zhang held a showcase to support the release of the single, which was held at the Century Theater in Beijing, EXO members Tao and Chen were guests, Exois a South Korean-Chinese boy group based in Seoul? 
Sentence (from "Exo (band)"): Formed by S.M. Entertainment in 2011, the group debuted in 2012 with twelve members separated into two subgroups, Exo-K (Suho, Baekhyun, Chanyeol, D.O., Kai, and Sehun) and Exo-M (Xiumin, Lay, Chen and former members Kris, Luhan and Tao ), performing music in Korean and Mandarin respectively.
Relevant evidence: No