Problem:
Factorial

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.

Sample Input

5

Output for the Sample Input

120

Solution in JavaScript (judge verdict: Accepted)

function main() {
  var
  i,
  fact = 1,
  n = parseInt(input, 10);
  for(i = 1; i <= n; i++) {
    fact *= i;
  }
  console.log(fact);
}
 
var
input = '';
 
process.stdin.resume();
process.stdin.setEncoding('utf8');
process.stdin.on('data', function(chunk) {
  input += chunk;
});
process.stdin.on('end', function() {
  main();
});