Go: package main

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

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func main() {
	scanner.Split(bufio.ScanWords)

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

C++: #include <iostream>
using namespace std;
int fact(int n){
  return n<=1?1:n*fact(n-1);
}
int main(){
  int n;

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

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

using namespace std;

int main()
{
  int n;
  scanf("%d",&n);
  int l = n;
  for(int i = 1;i < l;i++){
    n *=(l-i);
  }
  printf("%d",n);
  return 0;
}

C++: #include<iostream>

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

int main()
{
	int x;
	std::cin >> x;
	std::cout << fact( x ) << std::endl;

 	return 0;
}

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

using namespace std;

int main()
{
	int n;
	scanf("%d",&n);
	long long int now = 1;
	for(long long int i = 1; i <= n; i++)
	{
		now *= i;
	}
	printf("%lld\n",now);
	return 0;
}

C++: #include <iostream>

using namespace std;

void Solution()
{
    int n;
    
    cin>>n;
    
    int sum = n;
    
    for(int i = 0; i < n; i++)
    {
        sum = sum * (n - 1);
        n--;
    }
    
    cout << sum << endl;
    
    return;
}

int main()
{
    Solution();
    return 0;
}

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


int factorial_loop(int n);

int main(void)
{
  int n;
   int result1;


cin>>n;

if(0<n&&n<21) ;
else return 0;

	result1 =factorial_loop(n);

	cout<<result1;
	return 0;

}
int factorial_loop(int n) {
    int result = 1;
    int k;

    for(k = 1; k <= n; k++) {
        result *= k;
    }
    return result;
}

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

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

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

int main() {
	int n,ans=1;
	cin >> n;
	if (n <= 20 && n >= 0) {
		for (int a = 1; a <= n; a++) {
			ans = ans*a;
		}
		cout << ans << endl;
	}
}

C++: #include<iostream>

long int fac(int x) {
	if (x == 1) return 1;
	return x * fac(x - 1);
}

int main() {
	long int input;
	while (std::cin >> input) {
		std::cout << fac(input) << std::endl;
	}
	return 0;
}

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

C++: #include <iostream>

using namespace std;

int main() {
    int answer = 1;
    int n;
    cin >> n;

    for (int i = n; i != 0; i--) {
            answer *= i;
    }
cout << answer;
return 0;
}

C++: #include<cstdio>

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;
 
long factorial(long);
 
int main(void) 
{
    long long n;        
    cin >> n;
 
    cout << factorial(n) ; 
}
 
long factorial(long num) 
{
    long temp;
 
    if(num <= 1) return 1;
 
    temp = num * factorial(num - 1);  

    return temp;
}

C++: //NoorBaizura bt Mohd Zin
// 1111168

#include <iostream>

using namespace std;

int main()
{
    int x,count=1;
    
    cin >> x;
    
    if (x<=20)
    {
        for (int i=1; i<=x; i++)
            count *= i;
        
        cout << count;
    }
    
    else
        cout << "error";
    
//    system ("pause");
    return 0;
    
}

C++: #include <iostream>

using namespace std;

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

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

C++: #include<stdio.h>

int n;
long long output=1;

int main(){
	scanf("%d",&n);
	for(int i=n;i>=1;i--){
		output*=i;
	}
	printf("%lld\n",output);
	return 0;
}

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

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

int main()
{
 int n;
 long long int x;
 for(int i=1; i<n; i++)
{
 x=n*i;
cout<<x<<endl;
}
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 long n, res = 1;

	cin >> n;

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

	cout << res << endl;

	return 0;
}

C++: #include <iostream>
#include <cmath>
using namespace std;
int main() {
  int a = 0;
  cin >> a;
  cout << (long long)tgamma((long int)n + 1) << endl;
  return 0;
}

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

int main(){
    
    cin >> c;
    int ans = c;
    for(;c > 0;){
        
        if(c-1 != 0){
              ans = ans *(c-1);
             }
       
        
        c--;
          }
          
          cout << ans;
    system("pause");
    return 0;
    }

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

using namespace std;

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

C++: #include<cstring>
#include<cstdio>
#include<iostream>

using namespace std;


int main(){
int n, ans=1;

cin >> n;

while(n>1)	ans*=n--;

cout << ans << endl;

	return 0;
}

C++: #include <stdio.h>

int main(){
	int n;
	int x[40];
	int i,k;
	int Flag = 0;
	
	for(i = 0;i < 40;i++){
		x[i] = 0;
	}
	
	x[39] = 1;
	
	scanf("%d",&n);
	
	for(i = 1;i <= n;i++){
		for(k = 0;k <= 39;k++){
			x[k] *= i;
		}
		
		for(k = 39;k >= 0;k--){
			if(x[k] >= 10){
				x[k-1] += x[k]/10;
				x[k] %= 10;
			}
		}
	}
	
	for(i = 0;i < 40;i++){
		if(x[i] != 0){
			Flag = 1;
		}
		if(Flag == 1){
			printf("%d",x[i]);
		}
	}
	
	printf("\n");
	
	return 0;
}

C++: //Circumscribed Circle of a Triangle

#include<iostream>
using namespace std;

int fac(int n){
    if(n == 0 || n == 1) return 1;
    
    return (n * fac(n -1));
}

int main(void){
    int n, res;
    
    cin >> n;
    
    res = fac(n);
    
    cout << res << endl;
    
    return 0;
}

C++: #include<iostream>
#include<string>
#include<algorithm>
#include<map>
#include<set>
#include<utility>
#include<vector>
#include<cmath>
#include<cstring>
#include<cstdio>
#define loop(i,a,b) for(int i=a;i<b;i++) 
#define rep(i,a) loop(i,0,a)
#define rp(a) while(a--)
#define pb push_back
#define mp make_pair
#define all(in) in.begin(),in.end()
const double PI=acos(-1);
const double EPS=1e-10;
using namespace std;
typedef long long ll;
typedef vector<int> vi;
int main(){
	int n;
	ll out=1;
	cin>>n;
	rep(i,n)out*=i+1;
	cout<<out<<endl;
}

C++: #include <iostream>
#include <vector>
#include <algorithm>
#include <stack>
#include <string>
#include <map>
#include <functional>
#include <cmath>
#include <cstdio>
using namespace std;

long long ans = 1;

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

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

C++: #include <iostream>

using namespace std;

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

	int f = 1;
	for (int i = 1; i <= n; ++i)
		f *= i;

	cout << f << endl;

	return 0;
}