#P443. 【例78.1】忽明忽暗
【例78.1】忽明忽暗
Description
There are lights in the corridor, numbered from ,,,...,, managed by the school's circuit control center. Initially, all lights are off. A hacker has infiltrated the school's circuit control center and wants to make the lights flicker by performing rounds of operations. In the -th round, the hacker toggles the state of all lights whose numbers are multiples of (turning on lights that are off and turning off lights that are on).
The hacker wants to know the sum of the numbers of all lights that are on after rounds of operations. Since the answer might be very large, please output the result modulo .
Input Format
A single integer , representing the number of lights. For 100% of the test cases, .
Output Format
A single integer, representing the sum of the numbers of all lights that are on, modulo .
Sample
2030