Write a program which reads an integer n and prints the factorial of n. You can assume that n ≤ 20.



Input

An integer n (1 ≤ n ≤ 20) in a line.

Output

Print the factorial of n in a line.

Example

Input

5


Output

120
v = (1,
     1,
     2,
     6,
     24,
     120,
     720,
     5040,
     40320,
     362880,
     3628800,
     39916800,
     479001600,
     6227020800,
     87178291200,
     1307674368000,
     20922789888000,
     355687428096000,
     6402373705728000,
     121645100408832000,
     2432902008176640000)

print(v[int(input())])