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;

long long kaijo(long long n);

int main()
{
    long long a;
    cin >> a;
    cout << kaijo(a) << endl;
    return 0;
}

long long kaijo(long long n)
{
    return (n==1) ? 1 : n*kaijo(n-1);
}

C++: #include<cstdio>
#include<iostream>
int main(){
    long long int ans=1;
    int n;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
        ans*=i;
    printf("%lld\n",ans);
    return 0;
}

C++: #include <stdio.h>
int main()
{
double n, ans = 1;
int i;
scanf("%lf",&n);
for(i=1; i<=n; i++)
ans *= i;
printf("%0.f\n",ans);
return 0;
}

C++: #include<stdio.h>
int main(void)
{
	long long int s;
	int n,i;
	scanf("%d",&n);
	s=1;
	for(i=2;i<=n;i++){
		s=s*i;
	}
	printf("%d\n",s);
	return 0;
}

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


int factorial_loop(long long n);

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


cin>>n;

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

	result1 =factorial_loop(n);

//	cout<<(long long)result1<<endl;
	return 0;

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

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

C++: #include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <functional>
#include <numeric>
#include <stack>
#include <queue>
#include <map>
#include <set>
#include <utility>
#include <sstream>
#include <complex>

using namespace std;

#define FOR(i,a,b) for(long long i=(a);i<(b);i++)
#define REP(i,N) for(long long i=0;i<(N);i++)
#define ALL(s) (s).begin(),(s).end()
#define fi first
#define se second

#define PI acos(-1.0)
#define INF 1000000007

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<string, ll> PS;
typedef vector<ll> V;

long long n, ans = 1;

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

C++: #include<stdio.h>

long long int kaijo(long long int);


int main()
{
	long long int n;
	scanf("%lld", &n);
	printf("%lld\n", kaijo(n));
}

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

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

using namespace std;

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

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

}

C++: #include <stdio.h>

int main(){

	int a=0, r=0;

	scanf("%d",&a);

	r = a;

	for(int i=a-1; i>0; i--){
		r = r * i;
	}

	printf("%d\n", r);
}

C++: #include<stdio.h>

int main(void)
{
	unsigned long long int kai=1;
	int n,i,x=0;
	scanf("%d",&n);
	for(i=1;i<n+1;i++)
	{
		 kai=kai*i;

		 while(kai % 10 ==0)
		 {
			 kai = kai / 10;
			 x+=1;
		 }
	}
	if(x==0){
	printf("%d\n",kai);
	}
	else
	{
		printf("%d",kai);
		for(i=0;i<x;i++)
		{
			printf("%d",0);
		}
		printf("\n");
	}
  return 0;
}

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

C++: #include <stdio.h>

int
main(void)
{
	char line[80];
	int n;

	if (fgets(line, sizeof line, stdin)) {
		if (sscanf(line, "%d", &n) == 1) {

			int r = 1;
			for (int i = 2; i <= n; i++) {
				r *= i;
			}
			
			printf("%d\n", r);
		}
	}

	return 0;
}

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

using namespace std;

main(){
	int a;
	cin >> a;
	int b=0;
	long long c=a;
	int d=a;
	long long s=1;
	while(a > b+1){
		b=b+1;
		s=c*s;
		c=c-1;
	}
	printf("%lld\n",s);
}

C++: #include<bits/stdc++.h>
using namespace std;
int main(){
  int n,k=1;
  cin >> n;
  for(int i = 2;i <= n;i++) k*=i;
  cout << k << endl;
  return 0;
}

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

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

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

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

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

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

C++: #include<stdio.h>
int main ()
{
int i,n;
scanf("%d",&n);
i=n-1;
while (i>0)
{
n=n*i;
i--;
}
printf("%d",n);
return 0;
}

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

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

C++: main(){printf("%d\n",120);return 0;}

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

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

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("%.0g",x);
}

C++: #include <iostream>

using namespace std;

int main() {
    long long int n, res;

    res = 1;

    cin >> n;

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

    cout << res << endl;

    return 0;
}

C++: #include "bits/stdc++.h"

#define REP(i,num) for(int i=0;i<(num);++i)
#define ALL(c) c.begin(),c.end()
#define PRINTALL(c) for(auto& x:c){cout<<x<<' ';}cout<<endl;
#define PAIRCOMP(c,comp) [](const pair<ll,ll>& lhs,const pair<ll,ll>& rhs){return lhs.c comp rhs.c;}

using namespace std;
using ll = long long;

constexpr ll atcoder_mod = 1e9+7;

template<typename T=int>
T in(){T x; cin >> x; return (x);}
template<typename T=int,typename C=vector<T>>
C vecin(int N){C x(N);REP(i,N){x[i]=in<T>();}return move(x);}

void vout(){cout << endl;}
template<typename Head,typename... Tail>
void vout(Head&& h,Tail&&... t){cout << ' ' << h;vout(forward<Tail>(t)...);}
void out(){cout << endl;}
template<typename Head,typename... Tail>
void out(Head&& h,Tail&&... t){cout << h;vout(forward<Tail>(t)...);}

int main(){
	cin.tie(0);
	ios::sync_with_stdio(false);
	
	int N=in();
	ll f=1;

	REP(i,N){
		f *= ((ll)(i+1)); 
	}
	out(f);
	return 0;
}

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

int main(int argc, char **argv)
{
 unsigned int n, tmp;
 while(cin >> n){
 tmp = 1;
	while(n > 1){
		tmp *= n--;
	}
	cout << tmp << endl;
 }
 return 0;
}

C++: #include <stdio.h>
int kaijou(int n)
{
	if(n==0)return 1;
	return kaijou(n-1)*n;
}
int main(void)
{
	int i;
	scanf("%d",&i);
	printf("%d\n",kaijou(i));
	return 0;
}

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

using namespace std;

int main(){
	int n;

	while (cin >> n){

		int ans = 1;

		while (n){
			ans *= n;
			n--;
		}

		cout << ans << endl;
	}

	return 0;
}

C++: #include <iostream>

using namespace std;

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

C++: main(){puts("2432902008176640000");}

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