PROGRAM SUMAS (INPUT,OUTPUT);
VAR
SUM, W, X, Y, Z:LONGINT;

BEGIN

READLN(input, X);
     IF X>0 THEN
     BEGIN
        SUM:=0;
        FOR Y:=0 TO X DO

        SUM:=SUM+Y;
        WRITE(output, SUM);

     END
     ELSE IF X<=0 THEN
     BEGIN
          SUM:=0;
          FOR Y:=1 DOWNTO X DO

          SUM:=SUM+Y;
          WRITE(output, SUM);

    END;
END.

> PROGRAM SUMAS (INPUT,OUTPUT);
> VAR
> SUM, W, X, Y, Z:LONGINT;
>
> BEGIN
>
> READLN(input, X);
>      IF X>0 THEN
>      BEGIN
>         SUM:=0;
>         FOR Y:=0 TO X DO
>
>         SUM:=SUM+Y;
>         WRITE(output, SUM);
>
>      END
>      ELSE IF X<=0 THEN
>      BEGIN
>           SUM:=0;
>           FOR Y:=1 DOWNTO X DO
>
>           SUM:=SUM+Y;
>           WRITE(output, SUM);
>
>     END;
> END.



I don't know Pascal, but one thing is that the condition should X<1
and X>1 and X=0