Ehrenfest's urn

[zahi48g]

Ehrenfest's urn
Hi Everyone (from France )

I'm trying this algorythm on my prime without success , of course i've tried to debug .

EXPORT EHRENFEST1()
BEGIN
LOCAL n,p,K;
INPUT(p);
L1:={1,2};
L2:={};
FOR K FROM 1 TO p DO
n:=RANDINT(1,2);
IF L1(1)==n OR L1(2)==n THEN
L1:=SUPPRESS(L1,n);
L2:=INSERT(L2,1,n);
ELSE
L2:=SUPPRESS(L2,n);
L1:=INSERT(L1,1,n);
END;
END;
PRINT(L1);
PRINT(L2);
END;

Could you help me ?
It seems that the problem occurs when i write " n:=RANDINT(1,2); " .

Thank you .