MODULE HappyNumbers;
FROM InOut IMPORT WriteCard, WriteLn;

CONST Amount = 8;
VAR seen, num: CARDINAL;

PROCEDURE SumDigitSquares(n: CARDINAL): CARDINAL;
VAR sum, digit: CARDINAL;
BEGIN
    sum := 0;
    WHILE n>0 DO
        digit := n MOD 10;
        n := n DIV 10;
        sum := sum + digit * digit;
    END;
    RETURN sum;
END SumDigitSquares;

PROCEDURE Happy(n: CARDINAL): BOOLEAN;
VAR i: CARDINAL;
    seen: ARRAY [0..255] OF BOOLEAN;
BEGIN
    FOR i := 0 TO 255 DO
        seen[i] := FALSE;
    END;
    REPEAT
        seen[n] := TRUE;
        n := SumDigitSquares(n);
    UNTIL seen[n];
    RETURN seen[1];
END Happy;

BEGIN
    seen := 0;
    num := 0;
    WHILE seen < Amount DO
        IF Happy(num) THEN
            INC(seen);
            WriteCard(num,2);
            WriteLn();
        END;
        INC(num);
    END;
END HappyNumbers.