Factorial with long

Problem

In how many ways can n students stand in a line for a class photo? The answer is n factorial: n! = 1 × 2 × 3 × ... × n. By definition 0! = 1.

Read n and print n!.

Example 1

Input

Output

1 × 2 × 3 × 4 × 5 = 120.

Example 2

Input

Output

0! is 1 by definition.

Try the problem first. Open one hint at a time.

Hint 1

Start a product at 1, not 0.

Hint 2

Multiply it by 2, 3, ..., n in a loop. Store it in a long.

Write your Java code, run it on the examples and submit it to hidden tests.