Go: package main

import (
    "os"
    "fmt"
    "bufio"
    "strconv"
)

var sc = bufio.NewScanner(os.Stdin)
func readInt() int64 {
    sc.Scan()
    n, _ := strconv.Atoi(sc.Text())
    return int64(n)
}


func main() {
    var ans int64 = 1
    var n int64 = readInt()
    var i int64
    for i = 1; i <= n; i++ {
        ans *= i
    }
    fmt.Println(ans)
}

C++: #include <iostream>
#define MAX 5
using namespace std;

void HELLO();
int max(int x1, int x2);
int min(int x1, int x2);
int sum(int* array);
int fact(int n);

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

void HELLO(){ cout << "Hello!!" << endl; }

int max(int x1, int x2){ return x1 > x2 ? x1 : x2; } 
int min(int x1, int x2){ return x1 < x2 ? x1 : x2; }

int sum(int* array){
	int sumup = 0;
	for(int i = 0; i < MAX; i++) sumup += array[i];
	return sumup;
}

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

C++: #include <iostream>
#include <string>
#include <math.h>
#include <stdio.h>
#include <algorithm>

using namespace std;

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

C++: /*****include*****/
#include <iostream>
#include <fstream>
#include <string>

/*****デバッグ定義*****/
//#define DEBUG
/*****マクロ定義*****/

/*****名前空間*****/
using namespace std;

/*****グローバル変数置き場*****/

/*****その他関数置き場*****/

/*****main関数*****/
int main(){
	/*****ファイルオープン*****/
#ifdef DEBUG
	ofstream fout("output.txt");
	ifstream fin("input.txt");
	if(!fout || !fin){
		cout << "Can't open the file.\n";
		return;
	}
#endif
	/*****変数置き場*****/
	int n;
	long int res;
	/*****処理部*****/
	cin >> n;
	res = 1;
	if(n != 0){
		for(int i=2;i<=n;i++){
			res = res * i;
		}
	}
	cout << res << endl;
	/*****処理終了後*****/
#ifdef DEBUG
	fout.close();
	fin.close();
#endif
	return 0;
}

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

C++: #include <stdio.h>

long kai(long i){
		if(i==1||i==0){
			return 1;
		}
		return i*kai(i-1);
	}
int main(){

	long n;
	scanf("%d",&n);

	printf("%d\n",kai(n));
	return 0;

}

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

int main()
{
 int n;
 cin >> n;
 long long int ans = 1;
 for(int i=1; i<=n; i++) ans *= i;

 cout << ans << '\n';

 return 0;
}

C++: #include <iostream>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <string>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <functional>

using namespace std;

int main()
{
	unsigned long n, res = 1;

	cin >> n;

	for ( int i = 1; i <= n; i++ )
	{
		res *= i;
	}

	cout << res << endl;

	return 0;
}

C++: #include<cstdio>
#include<cstring>
#include<algorithm>
#include<functional>
using namespace std;
int main(void)
{
	int i,j,n;
	long long int sum;
	scanf("%d",&n);
	sum=1;
	for(i=2;i<=n;i++) sum=sum*i;
	printf("%lld\n",sum);
	return 0;
}

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

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

C++: #include<iostream>
using namespace std;
int main(){
  int n;

  while(cin>>n){
    int s=1;
    while(n>0){
      s*=n;
      n--;
    }
    cout<<s<<endl;
  }
  return 0;
}

C++: #include<iostream>

using namespace std;

int factorial(int n){
  int ans;
  if(n==0)
    ans=1;
  else
    ans =n*factorial(n-1);
  return ans;
}

int main(){
  int n=0;
  cin>>n;

  int ans=1;
  ans=factorial(n);

  cout<<ans;
}

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

C++: #include <cmath>
#include <iostream>
#include <string>
#include <cstdlib>
#include <cstdio>
#include <algorithm>
#include <sstream>

using namespace std;

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

C++: #include <iostream>
#include <cstdlib>
#include <windows.h>
using namespace std;

int main()
{
    long long n;
    
    do
    {
    cin >> n;
    
    }while(n>20);
    
    int x;
    long long sum=1;
    for(x=1; x<=n; x++)
    {
       sum = sum*x;
    }
    
    cout<< sum << endl;
    
    return 0;
}

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

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

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

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

long long fact(long long a){
  if(a<=1LL)return 1;
  return a*fact(a-1);
}

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

C++: #include <iostream>

using namespace std;

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

C++: #include <cstdio>
#include <cmath>
int main()
{
        int n,i,fac;
        scanf("%d",&i);
        fac=1;
        for(;i>1;i--)
                {
                        fac=fac*i;
                }

        printf("%d\n",fac);

        return 0;

}

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

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

int main(void)
{
	int n;

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

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

int main(){
	int n;
	int x=1;
	cin >> n;
	for (int i = 1; i <= n; i++){
		x = x*i;
	}
	cout << x;
}

C++: #include <iostream>

using namespace std;

int main() {
	int n;
	int re = 1;
	cin >> n;
	for(int i = 2; i < n; i++) {
		re *= n;
	}
	
	cout << re << endl;
	
	return 0;
	
}

C++:  
 #include<iostream>
 #include<stdio.h>
 #include<string>
 #include<math.h>
 #include<iomanip>
 #include<algorithm>
 #include<string.h>
 #include<cctype>
 #include<map>
 #include<set>
 #include<vector>
 #include<sstream>
 #include<stack>
 
 using namespace std;
  
 int main()
 {
   long long int n;
   long long result=1;
   cin>>n;
   while(n>1)
   {
     result*=n;    
     n--;
   }
   cout<<result<<endl;
   //while(1);      
   return 0;    
 }

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

int main(){
	int n;cin >> n;
	long long a = 1;
	 /*while(n){
	 	a*=n--;
	 }*/
	for(int i = 1;i <= n;i++)a*=i;
	cout << a << endl;
	return 0; 
}

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

long long functorial(long long ll){
  if(ll<=1) return 1;
  else return functorial(ll-1)*ll;
}

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

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

int main()
{
 int n;
 cin >> n;
 long long int ans;
 for(int i=1; i<=n; i++) ans *= i;

 cout << ans << '\n';

 return 0;
}

C++: #include <iostream>
#include <cstdint>

int main()
{
	std::uint32_t n;
	std::cin >> n;
	std::uint64_t factorial = 1;
	while (n > 0) {
		factorial *= n--;
	}
	std::cout << factorial << std::endl;
	return 0;
}

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

using namespace std;

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

#define MOD 1000000007
#define REP(i, N) for (int i = 0; i < N; ++i)
#define REP1(i, N) for (int i = 1; i <= N; ++i)
#define RREP(i, N) for (int i = N - 1; i >= 0; --i)
#define ALL(a) a.begin(), a.end()

int main() {
  int n;
  cin >> n;
  ll ans = 1;
  REP1(i, n) ans *= i;
  cout << ans << endl;
  return 0;
}