PALPRIM - Palindromic Primes (Hard)
A Palindromic number is a number without leading zeros that remains the same when its digits are reversed. For instance 5, 22, 12321, 101101 are Palindromic numbers where as 10, 34, 566, 123421 are not. A Prime number is a positive integer greater than 1 that has no positive divisors other than 1 and itself. For example, 2, 31, 97 are Prime numbers but 1, 10, 25, 119 are not. A Palindromic Prime number is both palindromic and prime at the same time. 2, 3, 131 are Palindromic Prime numbers but 6, 17, 3333 are not. Given a positive integer N, output the largest palindromic prime number not greater than N.
Input
The first line contains an integer T denoting the number of test cases. Each of the subsequent T lines contain a single integer N without leading/trailing spaces.
Output
Print T lines. For each test case, print a single integer denoting the largest palindromic prime number which does not exceed N.
Constraints
1 ≤ T ≤ 10^6
2 ≤ N ≤ 10^13
Example
Input: 3 2 10 666 Output: 2 7 383
Note Large input and output, please use faster I/O methods.
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Min_25:
2016-02-26 10:24:09
Please clarify the constraints on T and N.
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Added by: | sgtlaugh |
Date: | 2016-02-26 |
Time limit: | 15s |
Source limit: | 50000B |
Memory limit: | 1536MB |
Cluster: | Cube (Intel G860) |
Languages: | All except: ASM64 GOSU JS-MONKEY |
Resource: | Own Problem |