\begin{table}%t4
%\centering
\par
  % Cambia el alto de la fila, en porcentaje
\caption{Median values of ptp
%ptp
 amplitudes for objects with ($\Delta(I-K)~+$) and without ($\Delta(I-K)~-)$ IR excess.}
%\label{PTPvsQ}
\addtolength{\tabcolsep}{3.7pt}
\begin{tabular}{c|cc|cc|cc|cc|cc|cc} 
\hline 
\hline
& \multicolumn{4}{c|}{$R<R_{\rm cluster}$} & \multicolumn{4}{c}{$R>R_{\rm cluster}$}& \multicolumn{4}{|c}{Whole WFI field}\\
\hline
& \multicolumn{2}{c|}{$\Delta(I-K)+$} & \multicolumn{2}{c|}{$\Delta(I-K)-$}& \multicolumn{2}{c|}{$\Delta(I-K)+$} & \multicolumn{2}{c|}{$\Delta(I-K)-$}& \multicolumn{2}{c|}{$\Delta(I-K)+$} & \multicolumn{2}{|c}{$\Delta(I-K)-$}\\
\hline
Mass bins\tablefootmark{a}  & B& C & B& C & B& C & B& C & B& C & B& C \\  
\hline
$N$ & 44 &8 & 97 & 8 & 48 & 22 & 150 & 35 & 93 & 30 & 243 & 43 \\
%\hline
$\langle PTP \rangle$ [mag] &0.12 & 0.24& 0.05 & 0.16 & 0.11 &0.23 &0.03& 0.08 &0.12 &0.24&0.04&0.1\\
\hline
\end{tabular}
\tablefoot{\tablefoottext{a}{Mass bins as defined in Sect. 3: A is not shown due to the small sample number, B corresponds to the intermediate bin with $0.4< M < 0.075~M_\odot$ and C to the faint bin in which all objects have $\textit{M}< 0.075~M_\odot$.}}
\end{table}