program voda;
var r,s,a,put,i:longint;
    polje:array[1..10] of string[10];
begin
     readln(r,s);
     for i:=1 to r do readln(polje[i]);
     a:=r*s;
     i:=0;
     put:=1;
     repeat
      i:=i+1;
      if a>=2*i then begin
                          a:=a-2*i;
                          put:=put*i*i;
                     end
                else begin
                          a:=a-i;
                          put:=put*i;
                     end;

     until a<i;
      writeln(put);

end.