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
//------------------------------------------
#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 <queue>
#include <iterator>
#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 gcd(int a, int b){
   int tmp;
   while(a%b==0){
      tmp=a%b;
      a=b;
      b=tmp;
   }
}

int lcm(int a,int b){
   return a*b/gcd(a,b);
}

bool prime_number(int n){
   if(n < 2){
      return false;
   }
   else if(n == 2){
      return true;
   }
   if(n % 2 == 0){
      return false;
   }
   for(int i=3;i<=n/i;i+=2){
      if(n % i == 0) return false;
      return true;
   }
}

int main(){
   ULL a,ans=1;
   cin >> a;
   for(int i=1;i<=a;i++) ans*=i;
   cout << ans << endl;
}

C++: #include <cstdio>

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

C++: #include<stdio.h>

int main(void){
	double ans=1;
	int n,i;
	scanf("%d",&n);
	for(i=1;i<=n;i++)ans=ans*i;
	
	printf("%0.01f\n",ans);
return 0;
}

C++: 
 #include <string>
 #include <vector>
 #include <algorithm>
 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cmath>
 #include <queue>
 #include <map>
 #define INF 100000000
 
 using namespace std;
 typedef long long ll;
 
 ll num[21]={0};
 
 long long int kai(ll n){
 if(num[n]!=0)return num[n];
 else{
 num[n]=n*kai(n-1);
 return num[n];
 }
 }
 
 int main(){
 int n;
 num[0]=num[1]=1;
 cin>>n;
 cout<<kai(n)<<endl;
 }

C++: #include <cstdio>

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

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

using namespace std;

long long 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 <cstdio>
using namespace std;

unsigned long factorial(int n) {
     if(n > 1) return n * factorial(n-1);
     else return n;
}

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

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

int main() {
	unsigned long int x, ans=1;
	cin >> x;
	for (int i = 2; i <= x; i++) {
		ans *= i;
	}
	cout << ans<<endl;
}

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

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

C++: #include <iostream>

using namespace std;

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

	cin >> n;

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

	cout << fact << 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*=i;
cout<<x<<endl;
}
return 0;
}

C++: #include<iostream>

using namespace std;
long long sum(int n){
    if(n==1) return 1;
    if(n==2) return 2;
    return n*sum(n-1);
  
    }
    
    int main(){
        int n;
        cin>>n;
        cout<<sum(n)<<endl; 
        
        return 0;
    }

C++: #include<iostream>
using namespace std;
int main(){
	int n,i,ans=1;
	cin>>n;
	for(i=2;i<=n;i++){
		ans*=i;
	}
	cout<<ans<<endl;
	return 0;
}

C++: #include <stdio.h>

int main(void)
{
long long a;
int n;

scanf("%d", &n);

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

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

return (0);
}

C++: #include <iostream>
#include <stdio.h>
using namespace std;
int main(){
    int n;
    double x=1;
    cin >> n;
    for (int i=1;i<=n;i++){
        x*=i ;
    }
    // cout << x << endl;
    printf("%.0f\n",x);
}