For any two sets $S$ and $T$, $SΔT$ is defined as the set of all elements that belong to either $S$ or $T$ but not both, that is, $SΔT = (S\cup T) – (S\cap T)$. Let $A, B$ and $C$ be sets such that $A\cap B\cap C = \phi$, and the number of elements in each of $AΔB$, $BΔC$ and $CΔA$ equals $100$. Then the number of elements in $A\cup B\cup C$ equals
