I'm trying to create an if statment such that
if E1=a then 1
if E1=b then 2
if E1=c then 3
else all = 0

I've been trying the formula like so: if(E3=i,1,((E3=b,2),(E3=p,3,0))0)
I can't seem to get the formula to work. Can someone help me with this?

Thanks.