#include <iostream>
#include <cstring>
using namespace std;
const int RN = 1e5 + 10;
int a[RN], s[RN], n, len = RN - 1; 
 
void qj(int x) {
    for (int i = 0, k = 0; i < RN; ++i) {
        a[i] = a[i] * x + k;
        k = a[i] / 10;
        a[i] %= 10;
    }
}
 
void qh() {
    for (int i = 0, k = 0; i < RN; ++i) {
        s[i] += a[i] + k;
        k = s[i] / 10;
        s[i] %= 10;
    }
}
 
int main() {
    cin >> n;
    a[0] = s[0] = 1;
    for (int i = 2; i <= n; ++i)
        qj(i), qh();
    while (!s[len--]);
    for (int i = len + 1; i >= 0; --i) cout << s[i];
    return 0;
}