I am trying to formulate a constraint as follows ($X, Y, Z$ are either $-1$ or $1$): 

If $Z$ and $Y$ both equal $-1$, then $X$ must be $1$. But, if either $Z$ or $Y$ are not $-1$, then $X$ can be $-1$ or $1$.

I came up with $Z\cdot Y \le X$, but that limits $X$ to $1$ if both $Z$ and $Y$ are $1$ ($X$ can be $0$ if both are $1$).

Any advice on a more accurate constraint? 

Thank you.