You are given an integer n.
Return the largest prime number less than or equal to n that can be expressed as the sum of one or more consecutive prime numbers starting from 2. If no such number exists, return 0.
Example 1:
Input: n = 20
Output: 17
Explanation:
The prime numbers less than or equal to n = 20 which are consecutive prime sums are:
2 = 2
5 = 2 + 3
17 = 2 + 3 + 5 + 7
The largest is 17, so it is the answer.
Example 2:
Input: n = 2
Output: 2
Explanation:
The only consecutive prime sum less than or equal to 2 is 2 itself.
Constraints:
1 <= n <= 5 * 105