[USACO 2006 Ope l]Bedtime Reading
题号:NC25105
时间限制:C/C++/Rust/Pascal 1秒,其他语言2秒
空间限制:C/C++/Rust/Pascal 32 M,其他语言64 M
64bit IO Format: %lld

题目描述

Farmer John was performing his nightly bedtime reading duties for Bessie. "Oh, this gives me a headache," moaned Bessie.
"But it's just simple number theory," replied FJ. "Let's go over it again. The sigma function of a number is just the sum of the divisors of the number. So, for a number like 12, the divisors are 1, 2, 3, 4, 6, and 12. Summing them we get 28."
"That's all there is to it?" asked Bessie.
"Yep." replied FJ. "Perhaps someone will write a program to calculate the sigma function of an integer I (1 <= I <= 1,000,000)."

输入描述:

Line 1: A single integer, I

输出描述:

Line 1: The sum of all of I's divisors.
示例1

输入

复制
12

输出

复制
28