Prime Prime Power

We call a number a prime prime power when it can be written as $a^b$ where both the base $a$ and the exponent $b$ are prime. For example, $25 = 5^2$ and $27 = 3^3$ are prime prime powers because $5, 3$ are prime bases and $2, 3$ are prime exponents. Given two integers $n$ and $k$, find the $k$-th smallest prime prime power that is strictly greater than $n$.

The only line contains two integers $n$ and $k$ separated by a space ($1 \le n \le 10^{18}$, $1 \le k \le 100{,}000$).

Print a single integer $m$, the $k$-th smallest prime prime power that is strictly greater than $n$.