Continue in a While Loop

Source: Phước Hưng OJ

Version: Phuoc Hung OJ Extended

Problem Statement

Sum the integers from 1 to $n$ that are not divisible by 3, using while-loop logic. Advance the counter before continue. The result for $n=0$ is 0.

Input

One integer $0\le n\le10000$.

Output

Print the sum of integers not divisible by 3.

Subtasks

• Subtask 1 (20%): $0\le n\le 8$.

• Subtask 2 (30%): $0\le n\le 1000$.

• Subtask 3 (50%): $0\le n\le 10000$.

Examples

Example 1

Input:

6

Output:

12

Explanation:

Sum numbers from 1 to 6 excluding multiples of 3: 12.

Example 2

Input:

0

Output:

0

Explanation:

Sum numbers from 1 to 0 excluding multiples of 3: 0.