Function Digsum(n) =
    digsum := 0;
    while n>0 do
        digsum := digsum + n|10;
        n:=n\10;
    od;
    digsum.;

nadd := 0;
!!'Additive primes below 500 are';

for p=1 to 500 do
    if Isprime(p) and Isprime(Digsum(p)) then
       !!(p,' -> ',Digsum(p));
       nadd := nadd+1;
    fi od;

!!('There were ',nadd);