Any Hint?

I also have wa#20
Where's mistake?
But you've solved it, maybe you'll help me?
var i,n:integer;
cx,cy,x1,y1,x2,y2,x3,y3,x4,y4:integer;
x,y:array[1..102]of integer;
h,min,zn,ras1,ras2:real;
f:boolean;
begin
read(cx);read(cy);readln(n);
for i:=1 to n do readln(x[i],y[i]);
x[n+1]:=x[1];y[n+1]:=y[1];
f:=true;
zn:=0;
for i:=1 to n do begin
x1:=x[i]-cx;y1:=y[i]-cy;
x2:=x[i+1]-cx;y2:=y[i+1]-cy;
  if (zn=0)then begin
  zn:=x1*y2-x2*y1;
    if (zn=0)then begin
    if ((x[i]<=cx)and(cx<=x[i+1]))or((x[i]>=cx)and(cx>=x[i+1]))then f:=true
    else f:=false;
    break;break;break;
    end;
  end
  else begin
    if (zn*(x1*y2-x2*y1)<0)then begin
    f:=false;
    break;break;break;
    end;
  end;
end;
if (f=true)then write('0.000')
else begin
min:=0;
f:=false;
  for i:=1 to n do begin
  x1:=cx-x[i];y1:=cy-y[i];x2:=x[i+1]-x[i];y2:=y[i+1]-y[i];x3:=cx-x[i+1];y3:=cy-y[i+1];x4:=x[i]-x[i+1];y4:=y[i]-y[i+1];
    if (x1*x2+y1*y2>0)and(x3*x4+y3*y4>0)then begin
    x1:=x[i]-cx;y1:=y[i]-cy;x2:=x[i+1]-cx;y2:=y[i+1]-cy;
    h:=(abs(x1*y2-x2*y1))/(sqrt(sqr(x[i+1]-x[i])+sqr(y[i+1]-y[i])));
    end
  else h:=0;
  ras1:=sqrt(sqr(cx-x[i])+sqr(cy-y[i]));ras2:=sqrt(sqr(cx-x[i+1])+sqr(cy-y[i+1]));
  if (ras2<ras1)then ras1:=ras2;
  if (ras1<h)or(h=0)then h:=ras1;
    if (f=false)or(h<min)then begin
    min:=h;
    f:=true;
    end;
  end;
write((2*min):0:3);
end;
end.