I am in desperate need of help!

Suppose that X1,X2, . . . ,X100 are independent random variable, that Xi is

Poisson distributed with mean 2i − 1, and that N is another independent

random variable with N Bin(100, p). Let X = SUM(Xi) form i=1 to N .

How do I find the mean of X? Do I use the tower law? I don't know where to go from there though.