#include <bits/stdc++.h>

using namespace std;

ifstream fin("fact.in");
ofstream fout("fact.out");

int Descomp(int i)
{
     int d = 2;
     while(i > 1)
     {
         int p = 0;
         while(i % d == 0)
         {
             ++p;
             i /= d;
         }
         if(d == 5)
            return p;
         ++d;
     }
}

int main()
{
    int p, i = 0, d;
    fin >> p;
    if(p == 0)
        fout << 1;
    else
        while(p)
        {
            i += 5;
            p -= Descomp(i);
        }
    fout << i;
    return 0;
}