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- Project Euler #163: Cross-hatched triangles

# Project Euler #163: Cross-hatched triangles

# Project Euler #163: Cross-hatched triangles

_{This problem is a programming version of Problem 163 from projecteuler.net}

Consider an equilateral triangle in which straight lines are drawn from each vertex to the middle of the opposite side, such as in the *size 1* triangle in the sketch below.

Sixteen triangles of either different shape or size or orientation or location can now be observed in that triangle. Using *size 1* triangles as building blocks, larger triangles can be formed, such as the *size 2* triangle in the above sketch. One-hundred and four triangles of either different shape or size or orientation or location can now be observed in that *size 2* triangle.

It can be observed that the *size 2* triangle contains *size 1* triangle building blocks. A *size 3* triangle would contain *size 1* triangle building blocks and a *size n* triangle would thus contain *size 1* triangle building blocks.

If we denote as the number of triangles present in a triangle of size , then

You are given . Find .

**Input Format**

One integer is given on first line representing .

**Constraints**

- .

**Output Format**

Print one integer which is the answer.

**Sample Input**

```
2
```

**Sample Output**

```
104
```