Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func read() string {
	sc.Scan()
	return sc.Text()
}

func main() {
	sc.Split(bufio.ScanLines)
	n, _ := strconv.Atoi(read())
	sum := 1
	for i := n; i > 0; i-- {
		sum *= i

	}
	fmt.Println(sum)
}

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

unsigned long long int fact( int n ){
  if( n==0 )
    return 1;
  return n * fact( n-1 );
}

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

C++: //Vol0 0019
#include<stdio.h>
int main()
{
	int n,i,r=1;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		r*=i;
	}
	printf("%d\n",r);
	return 0;
}

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

using namespace std;


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

int main(){

	long long n;
	while(cin>>n)
		cout<<fuc(n)<<endl;


	return 0;
}

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

int fact(int n){
  if(n==2) return 2;
  else return n*fact(n-1);
}

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

C++: #include <iostream>

using namespace std;

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

int main()
{
    int n;
    int sum = 0;
    
    cin >> n;
    cout << fact(n) << endl;

    return 0;
}

C++: main(){printf("2432902008176640000\n");return 0;}

C++: #include<stdio.h>
long long facto(long n);
int main()
{
    long n;
    long long x;
    scanf("%ld",&n);
    x= facto(n);
    printf("%u\n",x);
    return 0;
}
long long facto(long n)
{
    if(n!=1)
     return n*facto(n-1);
}

C++: #include <iostream>
using namespace std;
int f(int n)
{
if (n == 1 || n == 2)
return 1;
return f(n-1)+f(n-2);
}
int main()
{
int n;
while (cin >> n)
cout << f(n) << endl;
return 0;
}

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

int main(){
 long long int n;
  while(cin >> n){
    if(1<=n && n<=20){
      for(int i=n-1;0<i;i--)
	n *= (long long int)i;
      cout << n << endl;
    }
  }
  return 0;
}

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

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

  }
  return 0;
}

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


int main(){
  int n,ans =1;
  scanf("%d", &n);

  for(int i=n;i>1;--i)
    ans*=i;
  printf("%d\n",ans);

  return EXIT_SUCCESS;
}

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

int main(){
    int n;
    cin >> n;
    long long int a=1;
    for(long long int i=2;i<=n;++i)a*=i;
    cout << a << endl;

    return 0;
}

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

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

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

int main(int argc, char *argv[]){
	int n;
	cin>>n;
	cout<<fact(n)<<endl;
    return 0;
}

C++: //  0019.cpp

#include <cstdio>
#include <cmath>

using namespace std;


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

C++: #include <bits/stdc++.h>

using namespace std;

int main()
{
    int n;
    cin >> n;
    cout << (long long)tgamma(n + 1) << endl;
    return 0;
}

C++: //include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <deque>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>

using namespace std;

//conversion
//------------------------------------------
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();}

//math
//-------------------------------------------
template<class T> inline T sqr(T x) {return x*x;}

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef long long LL;
typedef unsigned long long ULL;

//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))

//debug
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl;

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

int main() {
  int n;

  cin >> n;

  cout << factrial(n) <<endl;
}

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

C++: #include <cstdio>

int factorial(int number) {
	if (number == 1) {
		return 1;
	}
	return number * factorial(number - 1);
}

int main(int argc, char *argv[]) {
	int rcv;
	fscanf(stdin, "%d", &rcv);
	
	printf("%d\n", factorial(rcv));
	return 0;
}

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

int main() {
	ios :: sync_with_stdio(false);
	int n; cin >> n;
	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()
{
	long n, res = 1;

	cin >> n;

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

	cout << res << 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>

using namespace std;

int main(int argc, char *argv[]) {
  int n, result;
  cin >> n;
  result = n;

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

  cout << result;
  return 0;
}

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

using namespace std;

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

	scanf("%d",&n);
	for(int i = 2; i <= n; i++){
		ans *= i;
	}
	printf("%d\n",ans);

	return 0;
}

C++: #include <iostream>

int main(){
	int n,a=1;
	std::cin>>n;
	if(n<=20&&n>0){
	while(n!=0){
		a=a*n;
		n--;
	
	}
	
	std::cout<<a<<std::endl;
}
	return 0;
}

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

C++: #include <iostream>
#include <vector>
#include <utility>
#include <string>
#include <algorithm>
#include <numeric>
#include <cmath>
#include <string.h>
#include <deque>
#define REP(i,j,n) for(int i=j;i<n;i++)
#define SORT(x) sort(x.begin(),x.end())

using namespace std;



int main() {
	int n,sum=1;
	cin >> n;
	while (n > 1 ){
		sum *= n;
		n--;
	}

	cout << sum << endl;
	return 0;
}

C++: #include <iostream>

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