Contest Duration: - (local time) (100 minutes) Back to Home
A - A Recursive Function /

Time Limit: 2 sec / Memory Limit: 1024 MB

### 問題文

• f(0) = 1
• 任意の正整数 k に対し f(k) = k \times f(k-1)

このとき、 f(N) を求めてください。

### 制約

• N0 \le N \le 10 を満たす整数

### 入力

N


### 入力例 1

2


### 出力例 1

2


f(2) = 2 \times f(1) = 2 \times 1 \times f(0) = 2 \times 1 \times 1 = 2 です。

### 入力例 2

3


### 出力例 2

6


f(3) = 3 \times f(2) = 3 \times 2 = 6 です。

### 入力例 3

0


### 出力例 3

1


### 入力例 4

10


### 出力例 4

3628800


Score : 100 points

### Problem Statement

A function f(x) defined for non-negative integer x satisfies the following conditions:

• f(0) = 1;
• f(k) = k \times f(k-1) for all positive integers k.

Find f(N).

### Constraints

• N is an integer such that 0 \le N \le 10.

### Input

The input is given from Standard Input in the following format:

N


### Output

Print the answer as an integer.

### Sample Input 1

2


### Sample Output 1

2


We have f(2) = 2 \times f(1) = 2 \times 1 \times f(0) = 2 \times 1 \times 1 = 2.

### Sample Input 2

3


### Sample Output 2

6


We have f(3) = 3 \times f(2) = 3 \times 2 = 6.

### Sample Input 3

0


### Sample Output 3

1


### Sample Input 4

10


### Sample Output 4

3628800