#include <iostream>
#include <vector>
using namespace std;

// 计算阶乘的函数，返回存储阶乘结果的数组，低位在前
vector<int> factorial(int n) {
    vector<int> result(1, 1);  // 初始化为1，低位在前，方便计算
    for (int i = 2; i <= n; ++i) {
        int carry = 0;
        for (size_t j = 0; j < result.size(); ++j) {
            int product = result[j] * i + carry;
            result[j] = product % 10;
            carry = product / 10;
        }
        while (carry > 0) {
            result.push_back(carry % 10);
            carry /= 10;
        }
    }
    return result;
}

int main() {
    int n;
    cin >> n;
    if (n == 0 || n == 1) {
        cout << 1 << endl;
        return 0;
    }
    vector<int> res = factorial(n);
    // 从高位到低位输出结果
    for (auto it = res.rbegin(); it != res.rend(); ++it) {
        cout << *it;
    }
    cout << endl;
    return 0;
}