#include <fstream>
#include <vector>

using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
int n;
int main()
{
    fin>>n;
    if(n==0)
    {
        fout<<1;
        return 0;
    }
    int d=5;
    while(n!=0)
    {
        int k=0,cd=d;
        while(cd%5==0)
        {
            k++;
            cd/=5;
        }
        n-=k;
        d+=5;
    }
    fout<<d-5;
}