MODULE AdditivePrimes;
FROM InOut IMPORT WriteString, WriteCard, WriteLn;

CONST
    Max = 500;

VAR
    N: CARDINAL;
    Count: CARDINAL;
    Prime: ARRAY [2..Max] OF BOOLEAN;

PROCEDURE DigitSum(n: CARDINAL): CARDINAL;
BEGIN
    IF n < 10 THEN
        RETURN n;
    ELSE
        RETURN (n MOD 10) + DigitSum(n DIV 10);
    END;
END DigitSum;

PROCEDURE Sieve;
VAR i, j, max2: CARDINAL;
BEGIN
    FOR i := 2 TO Max DO
        Prime[i] := TRUE;
    END;

    FOR i := 2 TO Max DIV 2 DO
        IF Prime[i] THEN;
            j := i*2;
            WHILE j <= Max DO
                Prime[j] := FALSE;
                j := j + i;
            END;
        END;
    END;
END Sieve;

BEGIN
    Count := 0;
    Sieve();
    FOR N := 2 TO Max DO
        IF Prime[N] AND Prime[DigitSum(N)] THEN
            WriteCard(N, 4);
            Count := Count + 1;
            IF Count MOD 10 = 0 THEN WriteLn(); END;
        END;
    END;
    WriteLn();
    WriteString('There are '); WriteCard(Count,0);
    WriteString(' additive primes less than '); WriteCard(Max,0);
    WriteString('.');
    WriteLn();
END AdditivePrimes.