And,here it is:

program wx;
  var i,j,k,m,n:longint;
      b,c,s,t:extended;
  begin
    readln(n,c);
    dec(n);
    m:=trunc(sqrt(c));
    if m>=n then
      begin
        writeln('0.00');
        exit;
      end;
    if c/m<=m+1 then
      begin
        b:=m+c/m;
        s:=n*n-b*n+c;
      end
    else s:=1e100;
    inc(m);
    if c/m>=m-1 then
      begin
        b:=m+c/m;
        t:=n*n-b*n+c;
      end
    else t:=1e100;
    if s<t then writeln(s:0:2)
      else writeln(t:0:2);
  end.