program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

   var
   n, m, d, dn, dm, dns, dms, n1, m1, answer, x : integer;

   function teng(delta : integer) : integer;
   var
     ans : integer;

   begin
     ans := delta * 2;
     if odd(delta) and (odd(dn) or odd(dm)) then
       begin
         if odd(n1) then
           begin
             if odd(n) then dec(ans)
             else inc(ans)
           end
         else
           if odd(n) then inc(ans)
           else dec(ans);
       end;
     teng := ans;
   end;

begin
   read(m, n);
   if n < m then begin x := n;  n := m;  m := x;  end;
   n1 := TRUNC(sqrt(n));
   if sqr(n1)=n then dec(n1);
   m1 := TRUNC(sqrt(m));
   if sqr(m1)=m then dec(m1);
   d := n1-m1;
   dn := n - sqr(n1);
   dm := m - sqr(m1);
   dns := sqr(n1+1)-n;
   dms := sqr(m1+1)-m;
   if d = dn - dm then answer := teng(d)
   else
     begin
       if dm >= dn then begin writeLn(2*d+dm-dn);  exit  end;
       if dms >= dns then begin writeLn(2*d+dms-dns);  exit  end;
       if d > dn-dm then answer := (dn-dm)*2 + teng(d-dn+dm)
       else
         answer := (dns-dms)*2 + teng(d-dns+dms);
     end;
   writeLn(answer);
end.

Try to find other algoritm. On small test your program gives a right answers. But on this test: 119 751 answer is not true. Good luck! :)