dirpath:=proc(a,b,c)
	local dirtemp,dirnew,x;
	use StringTools in
		dirtemp:=LongestCommonSubString(c, LongestCommonSubString(a,b));
		x:=FirstFromRight("/",dirtemp);
		dirnew:=dirtemp[1..x];
	return dirnew;
	end use;
end proc;