Go: package main

import "fmt"

func main() {
	var n int
	fmt.Scan(&n)

	rs := 1
	for i := 1; i <= n; i++ {
		rs *= i
	}
	fmt.Println(rs)
}

C++: #include <iostream>
#include <sstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <climits>
#include <cfloat>
using namespace std;

long long factorial(int a) // ツ階ツ湘ヲ
{
    long long ret = 1;
    while(a > 0)
        ret *= a--;
    return ret;
}

int main()
{
    int n;
    cin >> n;
    cout << factorial(n) << endl;
}

C++: main(){puts("2432902008176640000");return 0;}

C++: #include <iostream>
using namespace std;

int main(){
	long long int n,ans=1;
	cin>>n;
	for(int i=n;i>0;i--){
		ans=ans*i;
}
	cout<<ans<<endl;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <string>

#define rep(x,to) for(int x=0;x<to;x++)
#define rep2(x,from,to) for(x=from;x<to;x++)

using namespace std;


int main(void){

unsigned long long su=1;;
int isu;
	
	cin >> isu;
	rep(i,isu)
		su *= isu - i;
	cout << su << endl;
	return 0;
}

C++: #include<stdio.h>
int ke(int x)
{
    if(x == 1)return 1;
    else return x*ke(x-1);
}
int main()
{
    int a;
    cin >> a;
    printf("%d",ke(a));
    return 0;
}

C++: #include<iostream>
#include<algorithm>
using namespace std;

int main()
{
    int n,m;
    
    cin>>n;if(n==0)n=1;m=n-1;
    while(m>0)
        n*=m--;
    cout<<n<<endl;
    return 0;
}

C++: #include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main(){
  int n,i;
  cin >> n;
  long long o=1;
  for(i=1;i<=n;i++) o*=i;
  cout << o << endl;
}

C++: #include <iostream>

using namespace std;

int main(){
    
    int num,fact=1;

    cout<<" Enter Number:  ";

    cin>>num;

if (num <=20){

          for(int a=1;a<=num;a++){
                  fact = fact * a;
                                  }

    cout<<fact<<endl;
    }
else
    cout<<"none";
   return 0;
   
}

C++: #include <iostream>
using namespace std;
 
// http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=0019

int main() {
	int d;
	cin >> d;
	long long int sum = 1;
	while (d > 1) sum *= d--;
	cout << sum << endl;
	return 0;
}

C++: #include <stdio.h>

int main(){
	int n;
	int i;
	long long ans=1;

	cin >> n;
	for(i=0; i<n; i++){
		ans = ans * (i+1);
	}
	cout << ans << endl;

	return 0;

}

C++: #include <iostream>

using namespace std;

typedef long long LL;

LL fact(int);

int main() {
    int n;
    cin >> n;
    cout << fact(n) << "\n";
    return 0;
}

LL fact(int n) {
    if (n == 1) 
        return 1;
    return fact(n-1) * n;
}

C++: #include<bits/stdc++.h>
using namespace std;
int main()
{
   long long n,rslt;
   rslt=1;
   cin>>n;
   for(i=1;i<=n;i++)
         rslt*=i;
    cout<<rslt<<endl;
    return 0;
}

C++: // clang-format off
#include <bits/stdc++.h>
#define int long long
#define main signed main()
// #define main int main()
#define loop(i, a, n) for (int i = (a); i < (n); i++)
#define rep(i, n) loop(i, 0, n)
#define all(v) (v).begin(), (v).end()
#define rall(v) (v).rbegin(), (v).rend()
#define prec(n) fixed << setprecision(n)
#define stlice(from, to) substr(from, (to) - (from) + 1)
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
using namespace std;
using pii = pair<int, int>;
using vi = vector<int>;
using vd = vector<double>;
using vc = vector<char>;
using vb = vector<bool>;
using vs = vector<string>;
using vpii = vector<pii>;
using vvi = vector<vi>;
using vvb = vector<vb>;
using vvpii = vector<vpii>;
template<typename A> using fn = function<A>;
constexpr int INF = sizeof(int) == sizeof(long long) ? 1000000000000000000LL : 1000000000;
constexpr int MOD = 1000000007;
constexpr double PI = acos(-1);
template<typename A, typename B> bool cmin(A &a, const B &b) { return a > b ? (a = b, true) : false; }
template<typename A, typename B> bool cmax(A &a, const B &b) { return a < b ? (a = b, true) : false; }
constexpr bool odd(const int &n) { return n & 1; }
constexpr bool even(const int &n) { return !odd(n); }
template<typename V> constexpr typename V::value_type sum(const V &v) { return accumulate(all(v), 0); }
void solve();
main { solve(); return 0; }
// clang-format on

int factorial(int n) {
  return n == 0 ? 1 : n * factorial(n - 1);
}

void solve() {
  int n;
  cin >> n;
  cout << factorial(n) << endl;
}

C++: #include <iostream>
#include <sstream>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <set>
#include <map>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <ctime>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;

#define all(c) (c).begin(), (c).end()
#define pb push_back
#define mp make_pair
#define EXIST(v,i) (find(all(v), i) != (v).end())
#define ERASE(v,i) (v).erase(remove(all(v), i), (v).end())
#define INDEX(v,i) (find(all(v), i) - (v).begin())
#define rep(i,n) for(int i = 0; i < (int)n; ++i)
#define debug(x) cerr << #x << " = " << (x) << endl;

inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

const int INF = 100000000;
const double PI = 3.14159265358979323846;
const double EPS = 1e-10;

ll factor(ll n) {
	return n == 1 ? 1 : n * factor(n - 1);
}

int main() {
	ll n; cin >> n;
	cout << factor(n) << endl;
	return 0;
}

C++: #include<stdio.h>

int main(){
	int x;
	scanf("%d", &x);

	for(int i = x - 1; i > 1; i--) x*=i;
	printf("%d\n", x);
	return 0;
}

C++: #include<iostream>
using namespace std;
int main() {
  int n;
  cin>>n;
  int ans=1;
  for(int i=1;i<=n;i++) 
    ans*=i;
  cout<<ans<<endl;
  return 0;
}

C++: #include <stdio.h>
int fact(int n){ return n>1 ? fact(n-1)*n : 1; }
int main(){
  int n;
  scanf("%d",&n);
  printf("%d\n",fact(n));
  return 0;
}

C++: c;main(){c=!puts("2432902008176640000");}

C++: #include<iostream>
using namespace std;
int main(){
int n;
int m=1;
cin>>n;
for(int i=0;i<n;i++){
m*=i+1;}
cout<<m<<endl;}

C++: #include <iostream>
using namespace std;
int rep(int n){
  if(n == 0)return 1;
  return n*rep(n-1);
}
int main(){
  int n;
  cin >> n;
  cout << rep(n) << endl;

}

C++: #include<cstdio>
using namespace std;

int ans[] = {1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800, 39916800, 479001600, 6227020800. 87178291200, 1307674368000, 20922789888000, 355687428096000, 6402373705728000, 121645100408832000, 2432902008176640000};

int main(){
  int a;
  scanf("%d", &a);
  printf("%d\n", ans[a - 1]);
  return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;
int main()
{
long long int n, sum=1;
cin>>n;
for(int i=2; i<=n; i++){sum*=i;}
cout<<sum<<endl;


return 0;
}

C++: #include<iostream>
using namespace std;
long long int kaizyo(int x){
  if(x<2)return 1;
  return x*kaizyo(x-1);
}
int main(){
  int n;
  long long int a;
  cin>>n;
  a=kaizyo(n);
  cout<<a<<endl;
}

C++: #include <iostream>

using namespace std;

long factorial(long n)
{
    if (n == 0) return 1;
    
    return n * factorial(n - 1);
}

int main()
{
    long n;
    
    cin >> n;
    
    cout << factorial(n) << endl;
}

C++: #include<iostream>
using namespace std;
main(){
	int a;
	long long int ans=1;
	cin>>a;
	for(int i=1;i<=a;++i){
		ans*=i;
	}
	cout<<ans<<endl;
}

C++: #include <iostream>

using namespace std;

int fact(int n) {
	if (n == 1) { return n; }
	if (n > 1) { n *= fact(n - 1); }
}

int main() {
	int n;
	cin >> n;
	cout << fact(n) << endl;
	return 0;
}

C++: #include <iostream>
#include <string>
#include <algorithm>
using namespace std;
typedef long long LL; 

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int n;
	cin >> n;
	
	LL ans = 1;
	while(n > 0){
		ans *= n;
		n--;
	}
	
	cout << ans << endl;
		
	return 0;
}