How many months after the truce of the War of Independence was called did the entire island of Ireland become the Irish Free State?
return the  truce of   the   War of Independence was  called ;return the  entire island of   Ireland become the   Irish Free State ;return month of   #1 ;return month of   #2 ;return the  difference of   #4 and  #3
['select', 'select', 'project', 'project', 'arithmetic']