Let $A=\{x\ |\ x\in\mathbb Z_{\ge 0},\ x\ $ with some conditions$\ \}$. Let $B=\mathbb Z_{\ge 0}-A$. Define $\ 2A= \{a+b : a \in A,\ b \in A\}$. Define $\ 2B=\{a+b : a \in B,\ b \in B\}$. Then the set $\ \{n,\ n+1,\ n+2, \ ...\}\ \subseteq\ 2A\ $or $\ 2B$ for some nonnegative integer $n$?