+# Verbosity flag (empty show nice messages, non-empty use make messages)
+# When used internal, $V expand to @ is nice messages should be printed, this
+# way it's easy to add $V in front of commands that should be silenced when
+# displaying the nice messages.
+override V := $(if $V,,@)
+# honour make -s flag
+override V := $(if $(findstring s,$(MAKEFLAGS)),,$V)
+
+targets := presentacion.pdf notas.pdf
+
+.PHONY: all
+all: $(targets)
+