SNR in one-dimensional additive channel with uniform noise and binary antipodal input

A one-dimensional addictive noise channel, $Y=X+N$, has uniform noise distribution $N \sim U(-\frac{L}{2}, \frac{L}{2})$ and binary antipodal input constellation with equally likely input values $x=\pm 1$. Find $\rm SNR$ as a function of $L$.

I know that the $\rm SNR = \frac{\rm Signal \, \,Power}{Noise \, \,Power}$, yet I couldn’t figure out how to find these power. Any hints?

Signal power $=E[X^2]$; Noise power $=E[N^2]$. I assume that you know how to calculate these expectations.