[usaco3.2.1]fact4

/*
ID:abc31261
LANG:C++
TASK:fact4 
*/
#include<cstdio>
#include<cstring>
#include<iostream>
using namespace std;
const int maxn=5000;
int num[maxn],len;

void cheng(int numa)
{
     int i,x=0;
     for (i=1;i<=len;i++)
     {
         num[i]=num[i]*numa+x;
         x=num[i]/10;
         num[i]=num[i]%10;
     }
     while (x!=0)
     {
           num[++len]=x%10;
           x=x/10;
     }
}     
int main()
{
    long long i,n;
    freopen("fact4.in","r",stdin);
    freopen("fact4.out","w",stdout);
    cin>>n;
    len=num[1]=1;
    for (i=2;i<=n;i++)cheng(i);
    for (i=1;num[i]==0 && i<=len;i++){}
    cout<<num[i]<<endl; 
    return 0;
}