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Sum of divisors - MarisaOJ: Marisa Online Judge

Sum of divisors

Time limit: 1000 ms
Memory limit: 256 MB

Calculate the sum of positive divisors of given integer n.

Input

  • An integer n.

Output

  • The sum of positive divisors n.

Constraints

  • 1≤n≤1012.

Example

Input:

10

Output:

18