Go: package main

import (
        "fmt"
)

func main() {
        var n int
        fmt.Scanf("%d", &n)
        fmt.Println(fact(n))
}

func fact(n int) (f uint64) {
        if n < 2 {
                return uint64(1)
        } else {
                return fact(n-1) * uint64(n)
        }
}

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

int main(){

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

	cout << x << endl;

	return 0;
}

C++: #include <stdio.h>
#include <iostream>
using namespace std;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
typedef long long Int;

Int f(int n) {
    Int r = 1;
    rep (i, n) r *= i+1;
    return r;
}

int main() {
    int n;
    scanf("%d", &n);
    cout << f(n) << endl;
    return 0;
}

C++: #include <iostream>
using namespace std;
int main(void){
    // Here your code !
    int n,a=1;
    cin>>n;
    
    for(int i=1;i<=n;i++){
        a=a*i;
    }
    cout<<a<<endl;
}

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

int main() {
  int n;
  cin >> n;
  int ans = n;
  while (--n)
    ans *= n;
  cout << ans << endl;
}

C++: #include<stdio.h>

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

C++: #include <stdio.h>
int main()
{ int n, count;
unsigned long long int factorial=1;
while(scanf("%d",&n)==1)
{
     if ( n== 0)
     printf("1\n");
     else
     {
         for(count=1;count<=n;++count)
     { factorial=factorial*count;}
      printf("%llu\n",factorial);
      }
      }
      return 0;
       }

C++: #include <stdio.h>

int factrial(int n)
{
	int fac;
	
	if(n == 1){
		return (1);
	}
	
	else{
		fac = factrial(n - 1) * n;
		if(fac >= 0){
			return (fac);
		}
		else{
			return(-1 * fac);
		}
	}
}

int main(void)
{
	int n;
	scanf("%d", &n);
	printf("%d\n", factrial(n));
	
	return (0);
}

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

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

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

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

C++: #include<bits/stdc++.h>
using namespace std;


int main(){
int a;
long long sum=1;
	cin>>a;
	for (int i = a; i > 0; --i) {
		sum*=i;
	}
cout<<sum;
}

C++: #include<iostream>

int main(){
  int n,ans=1;
  std::cin >> n;
  while(n!=0){
    ans *= n;
    --n;
  }
  std::cout << ans << std::endl;
}

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

int main(){
int n,b=0;
bool a=false;
int ans[30];
ans[0]=1;
for(int i=1;i<30;i++){
ans[i]=0;}
cin>>n;
for(int i=2;i<n+1;i++){
for(int j=0;j<30;j++){
ans[j]*=i;
ans[j]+=b;
if(ans[j]<10)b=0;
if(ans[j]>=10){
b=(ans[j]-ans[j]%10)/10;
ans[j]%=10;
}
}
}
for(int i=29;i>-1;i--){
if(ans[i]!=0){
a=true;}
if(a){
cout<<ans[i];}}
cout<<endl;}

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

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

	for(int i=1; i <=n; i++){
		ans += i;
	}
	cout << ans << endl;
}

C++: #include <iostream>

using namespace std;

int main(){
	long double n; cin >> n;
	if(n <= 1){
		cout << 1;
	}else{
		for(int i = n - 1; i > 0; i--)
			n *= i;
		cout << n;
	}
	return 0;
}

C++: #define _USE_MATH_DEFINES
#include <iostream>
#include <sstream>
#include <cmath>
#include <algorithm>
#include <queue>
#include <stack>

typedef long long ll;
using namespace std;

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

int main()
{
	ll n;
	scanf("%lld",&n);
	cout << fact(n) << endl;
}

C++: #include<iostream>
main(){long n,i;std::cin>>n;for(i=n;--n;)i*=n;std::cout<<i<<"\n";}

C++: #include <iostream.h>
#include <conio.h>
using namespace std;
int main()
{
	int n=0, fact=1;
	 cout<<"Enter a number:";
	 cin>>n;

	 for(int i=n; i>=1; i--)
     fact*=i;
	 cout<<"Factorial for the number is: "<<fact<<endl;
     getchar();


	system("pause");
	return 0;
}

C++: #include<bits/stdc++.h>
using namespace std;

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

	long long ans = n;
	while(--n >= 1){
		ans *= n;
	}
	cout << ans << endl;
}

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

int main(){
  int n;
  while(cin>>n){
    int c=1;
    if(n==0)c=0;
    else
      for(int i=n;i>0;i--)
	c*=i;
    cout<<c<<endl;

  }
  return 0;
}

C++: #include<iostream>
double input=0;

void factorial(double& i__)
{
	double result=1;
	for(int i=i__;i>0;i--)
	{
		result*=i;
	}

	std::cout<<result<<std::endl;

}

int main()
{
	std::cin>>input;
	while(input<=20&&input>=0)
	{	
		factorial(input);
		std::cin>>input;
	}


	return 0;
}

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

using namespace std;

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

	uint64_t f = 1;
	for (int i = 1; i <= n; ++i)
		f *= i;

	cout << f << endl;

	return 0;
}

C++: #include<cstdio>


using namespace std;
int main(void)
{
	int a;
	double b = 1;
	scanf("%d",&a);
	for(int i = 1;i<=a;i++)
	{
		b = b * a;
	}
	printf("%.0lf\n",b);
	return 0;
}

C++: #include<iostream>

using namespace std;

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

C++: #include <algorithm>
#include <sstream>
#include <iostream>
#include <list>
#include <map>
#include <math.h>
#include <stack>
#include <stdio.h>
#include <string>
#include <queue>
#include <vector>
using namespace std;

long long int factorial(int n) {
	if (n == 1) return n;

	return n * factorial(n - 1);
}

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

C++: #include<iostream>
int main(){
	int n;
	std::cin>>n;
	int a=1;
	if(n<=12){
		for(int i=1;i<=n;i++){
			a*=i;
		}
		std::cout<<a<<std::endl;
	}
	else if(n==13)std::cout<<355687428096000/16/15/14/13;
	else if(n==14)std::cout<<355687428096000/16/15/14;
	else if(n==15)std::cout<<355687428096000/16/15;
	else if(n==16)std::cout<<355687428096000/16;
	else if(n==17)std::cout<<355687428096000;
	else if(n==18)std::cout<<355687428096000*18;
	else if(n==19)std::cout<<355687428096000*18*19;
	else if(n==20)std::cout<<355687428096000*18*19*20;
	

	return 0;
}

C++: #include<stdio.h>
int main()
{
  long long int n,res;
    int i;
    while(scanf("%lld",&n)==1){
            res=1;

        for(i=2;i<=n;i++){
            res=res*i;
        }

   printf("%lld\n",res);

    }



   return 0;


    }

C++: #include <iostream>
#include<math.h>
#include<iomanip>
#include<vector>
#include<algorithm>
#include<functional>
using namespace std;

int main()
{
    int  a=0,b=0,i=0;
    cin >> a;
    b=1;
    for(i=0;i<a;i++){
        b=b*(i+1);
    }

    cout << b << endl;



    //cout << endl;

return 0;

}

C++: #include<stdio.h>
#include<string.h>
int main()
{
    int a,b,c,d,ans,cnt;

    while(scanf("%d",&ans)==1)
    {
        for(a=0,cnt=0;a<10;a++)
            for(b=0;b<10;b++)
                for(c=0;c<10;c++)
                    for(d=0;d<10;d++)
                        if(a+b+c+d==ans)
                            cnt++;
        printf("%d\n",cnt);
    }
}

C++: #include <iostream>

using namespace std;

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

C++: #include<stdio.h>
long long int numbers[21];
int last_added=1;

long long int facto(int key)
{
	long long int m = 1;
	
	if (numbers[key] != 0)
		return numbers[key];
	
	else
	{
		for (int i = last_added; i <= key; i++)
		{
			if (numbers[i] != 0)
			{
				m *= numbers[i];
			}
			else
			{
				m *= i;
				numbers[i] = m;
				if (i > last_added)
					last_added = i;
			}
		}
		return m;
	}
}
int main()
{
	int n;
	while (scanf("%d", &n))
	{
		printf("%lld\n", facto(n));
	}
	return 0;
}