#include<iostream>
#include<fstream>
using namespace std;
int functie(int &n)
{
    long long int v[13]={5,25,125,625,3125,15625,78125,390625,1953125,9765625,48828125,244140625,1220703125};
    int i,q=0;
    for(i=1;i<=12;)
    {
        if(n>v[i])
        {
            n-=i*5;
        }
        i++;
    }
}
int cati5(int x)
{
    int q=0;
    while(x%5==0)
        q++,x/=5;
    return q;
}
int main()
{
    int p;
    ifstream fin("fact.in");
    fin>>p;
    fin.close();
    int n=5,i,aux;
    while(p>0)
    {
        p--;
        n+=5;
    }
    n-=5;
    if(n>25)
        functie(n);
    ofstream fout("fact.out");
    fout<<n;
    fout.close();
    return 0;
}