Program Stovykla;

  procedure Ivesk (var M, V: integer);
    var inp : text;
  begin
    assign(inp, 'valtis.dat');
    reset(inp);
    read(inp, M, V);
    close(inp);
  end; { Įvesk }

  procedure Isvesk (nepavyks: boolean; sk: integer);
  begin
    if nepavyks
       then writeln ('NEPAVYKS')
       else writeln (sk);
  end; { Išvesk }

  procedure Sprendimas (M, V: integer;
                        var nepavyks: boolean; var sk: integer);
  begin
    nepavyks := (M = 0) and (V > 1) or (M = 1) and (V >= 1);
    if (V = 1) and (M = 0) or (M = 1) and (V = 0)
              then sk := 1
              else sk := V*4+(M-2)*2+1;
  end; { sprendimas }

  var M, V, sk : integer;
      nepavyks: boolean;
begin
  Ivesk(M, V);
  Sprendimas(M, V, nepavyks, sk);
  Isvesk(nepavyks, sk);
end.