for each nonterminal X do First(X) :={}
while there are changes to any First(X) do
for each production rule X ->X1X2...Xn do
k:=1;
while k<=n do
First(X) = First(X) U (First(Xk)-{ε})
if ε is not in First(Xk) then break;
k := k+1;
if (k>n) then First(X) = First(X) U {ε}
follow sets
stmt -> if-stmt|other if-stmt -> if(exp)stmt else-part else-part -> else stmt | ε exp -> 0 | 1
