#include<fstream>
using namespace std;
int main()
{
    ifstream read("fact.in");
    ofstream write("fact.out");
    int P;
    read>>P;
    int e5=0;
    if(P==0)
    {
        write<<1;
    }
    else
    {
        int n=5,ncpy;
        while(1)
        {
            ncpy=n;
            while(ncpy%5==0)
            {
                e5=e5+1;
                ncpy=ncpy/5;
            }
            n=n+5;
            if(e5>=P)
            {
                write<<n-5;
                break;
            }
        }
    }
}