#include<iostream>
#include<fstream>
using namespace std;

fstream fin("fact.in", ios::in);
fstream fout("fact.out", ios::out);

int main()
{
    ios::sync_with_stdio(false);
    unsigned int p; fin>>p;

    if(p == 0)
        fout<<1;
    else
    {
        long long unsigned int i = 5;
        long long unsigned int counter = 0;

        for(;counter <= p; i+=5)
        {
            long long unsigned cop = i;

            while(cop % 5 == 0)
            {
                counter ++;
                cop /= 5;
            }
            //cout<<counter<<"\n";
        }

        fout<<i - 5;
    }
}