print((function (f, fh)
	local _,t = fh:read("*l"),fh:read("*l")
	if t:find(" ") then return "assert" end
	local i,j,k = tonumber(t),fh:read("*n"),fh:read("*n")
	local a = f({i+j;j+k;k+i})
	return a[2]==a[3] and a[1] or a[2]
end)(function (a)
	for i=2,#a do
		local t,j=a[i],i
		while j>1 and a[j-1]>t do j=j-1 a[j+1]=a[j] end
		a[j]=t
	end
	return a
end, io.stdin))