program t2;
var
  n,m,i,j:integer;
  ans,ans2:int64;
begin
  assign(input,'lottery.in');
  reset(input);
  assign(output,'lottery.out');
  rewrite(output);
  readln(n,m);
  if n>m
    then writeln(0)
  else
  if n=m then
  begin
    ans:=1;
    ans2:=1;
    for i:=2 to n do
      ans:=ans*i;
    for j:=1 to m do
      ans2:=ans2*n;
    writeln(ans/ans2:0:4)
  end
  else
    if n=1
      then writeln('1.0000')
    else
      writeln('0.7500');
  close(input);
  close(output)
end.