# Climb Stairs

easy

1. You are given a number n, representing the number of stairs in a staircase. 2. You are on the 0th step and are required to climb to the top. 3. In one move, you are allowed to climb 1, 2 or 3 stairs. 4. You are required to print the number of different paths via which you can climb to the top.

## Constraints

0 <= n <= 20

## Format

### Input

A number n

### Output

A number representing the number of ways to climb the stairs from 0 to top.

## Example

Sample Input

4

### Sample Output

7

Question Video