// Ces programmes sont sous licence CeCILL-B V1.
class Factorielle {

  public static void main (String [] args) {
    int n, i, f;
    n = Isn.readInt();
    f = 1;
    for (i = 1; i <= n; i = i + 1) {
      f = f * i;}
    System.out.println(f);}}