D. Rotatable Numbertime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputBike is a smart boy who loves math very much. He invented a number called "Rotatable Number" inspired by 142857. As you can see, 142857 is a magic number because any of its rotatings can be got by multiplying that number by 1, 2, ..., 6 (numbers from one to number's length). Rotating a number means putting its last several digit into first. For example, by rotating number 12345 you can obtain any numbers: 12345, 51234, 45123, 34512, 23451. It's worth mentioning that leading-zeroes are allowed. So both 4500123 and 0123450 can be obtained by rotating 0012345. You can see why 142857 satisfies the condition. All of the 6 equations are under base 10.  142857·1 = 142857;  142857·2 = 285714;  142857·3 = 428571;  142857·4 = 571428;  142857·5 = 714285;  142857·6 = 857142. Now, Bike has a problem. He extends "Rotatable Number" under any base b. As is mentioned above, 142857 is a "Rotatable Number" under base 10. Another example is 0011 under base 2. All of the 4 equations are under base 2.  0011·1 = 0011;  0011·10 = 0110;  0011·11 = 1001;  0011·100 = 1100. So, he wants to find the largest b (1 < b < x) so that there is a positive "Rotatable Number" (leading-zeroes allowed) of length n under base b.Note that any time you multiply a rotatable number by numbers from 1 to its length you should get a rotating of that number.InputThe only line contains two space-separated integers n, x (1 ≤ n ≤ 5·106, 2 ≤ x ≤ 109). OutputPrint a single integer — the largest b you found. If no such b exists, print -1 instead. ExamplesInput6 11Output10Input5 8Output-1
Input6 11
Output10
['math', 'number theory', '*2600']