BEGIN

% RETURN N MOD M %
INTEGER FUNCTION MOD(N, M);
INTEGER N, M;
BEGIN
  MOD := N - (N / M) * M;
END;

% RETURN 1 IF N IS PRIME, OTHERWISE 0 %
INTEGER FUNCTION ISPRIME(N);
INTEGER N;
BEGIN
  IF N = 2 THEN
    ISPRIME := 1
  ELSE IF (N < 2) OR (MOD(N,2) = 0) THEN
    ISPRIME := 0
  ELSE % TEST ODD DIVISORS UP TO SQRT OF N %
    BEGIN
      INTEGER I, DIVISIBLE;
      I := 3;
      DIVISIBLE := 0;
      WHILE (I * I <= N) AND (DIVISIBLE = 0) DO
        BEGIN
          IF MOD(N,I) = 0 THEN DIVISIBLE := 1;
          I := I + 2;
        END;
      ISPRIME := 1 - DIVISIBLE;
    END;
END;

% RETURN THE SUM OF THE DIGITS OF N %
INTEGER FUNCTION SUMDIGITS(N);
INTEGER N;
BEGIN
  INTEGER SUM;
  SUM := 0;
  WHILE N > 0 DO
     BEGIN
        SUM := SUM + MOD(N, 10);
        N := N / 10;
     END;
  SUMDIGITS := SUM;
END;

% LOOK FOR ADDITIVE PRIMES IN RANGE 1 TO 500 %
INTEGER I, S, COUNT;
COUNT := 0;
FOR I := 1 STEP 1 UNTIL 500 DO
  BEGIN
    IF ISPRIME(I)=1 THEN
      BEGIN
        S := SUMDIGITS(I);
        IF ISPRIME(S)=1 THEN
          BEGIN
            WRITEON(I);
            COUNT := COUNT + 1;
            IF MOD(COUNT,8) = 0 THEN WRITE("");
          END;
      END;
  END;
WRITE(COUNT," ADDITIVE PRIMES WERE FOUND");

END