inverse:=func(d,m);
r:=[1..25];
for j in [1..25] do
   r(j):=0;
end;
q:=r;
s:=r;
t:=r;
u:=r;
v:=r;
s(1):=1;
v(1):=1;
r(1):=m;
r(2):=d;
j:=2;
while r(j)>1 do
   q(j-1):=floor(r(j-1)/r(j));
   r(j+1):= r(j-1)-q(j-1)*r(j);
   s(j):=u(j-1);
   t(j):=v(j-1);
   u(j):=s(j-1)-q(j-1)*u(j-1);
   v(j):=t(j-1)-q(j-1)*v(j-1);
   j:=j+1;
end;
if r(j)=1 then return v(j-1) mod m; else return ' no inverse, GCD is not 1'; end;
end;