2022-09-05

#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <iomanip>
using namespace std;

int main()
{
    int n, a[1001] = { 0 }, b[1001] = { 0 },i,j;
    cin >> n;
    a[0] = b[0] = 1;
    for (i = 2; i <= n; i++)
    {
        for (j = 0; j < 100; j++)
            a[j] *= i;
        for (j = 0; j < 100; j++)
        {
            if (a[j] > 9)
            {
                a[j + 1] += a[j] / 10;
                a[j] %= 10;
            }
        }
        for (j= 0; j < 100; j++)
        {
            b[j] += a[j];
            if (b[j] > 9)
            {
                b[j + 1] = b[j] / 10;
                b[j] %= 10;
            }
        }
    }
    for (i=100; i>=0 && b[i]==0;i--);
    for (j=i; j >= 0; j--)
        cout << b[j];
    system("pause");
    return 0;
}