Light traveling through medium $3($n$3=2\mathrm{.}6)$ is incident on the interface with medium $2($n$2=2\mathrm{.}2)$ at angle $.$ There is a range of values for such that light does enter into medium $2$ and then does not enter into medium $1($n$1=1\mathrm{.}3).$The upper limit on for this to occur is $<\_\_\_\_.$