A10859. k-th divisor
编程题
普及/提高-
知识点
题目描述
You are given two integers $n$ and $k$ . Find $k$ -th smallest divisor of $n$ , or report that it doesn't exist.
Divisor of $n$ is any such natural number, that $n$ can be divided by it without remainder.
Divisor of $n$ is any such natural number, that $n$ can be divided by it without remainder.
输入格式
The first line contains two integers $n$ and $k$ ( $1<=n<=10^{15}$ , $1<=k<=10^{9}$ ).
输出格式
If $n$ has less than $k$ divisors, output -1.
Otherwise, output the $k$ -th smallest divisor of $n$ .
Otherwise, output the $k$ -th smallest divisor of $n$ .
输入输出样例
输入 #1
4 2
输出 #1
2
输入 #2
5 3
输出 #2
-1
输入 #3
12 5
输出 #3
6
说明/提示
In the first example, number $4$ has three divisors: $1$ , $2$ and $4$ . The second one is $2$ .
In the second example, number $5$ has only two divisors: $1$ and $5$ . The third divisor doesn't exist, so the answer is -1.
In the second example, number $5$ has only two divisors: $1$ and $5$ . The third divisor doesn't exist, so the answer is -1.