#include<iostream>
using namespace std;
int main()
{
    int num;
    cin>>num;
    try
    {
        int final=1;
        if(num<0)
        {
            throw "Invalid input";
        }
        if(num<1 || num>12)
        {
            throw "Overflow occured";
        }
        for(int i=0;i<num;i++)
        {
          final*=num[i];  
        }
        cout<<final;
    }
    catch(const char* msg)
    {
        cout<<msg;
    }
    return 0;
}