#include <iostream>
#include <fstream>

using namespace std;

ifstream f("fact.in"); ofstream g("fact.out");
int n,x; long long i;

int main()
{
    f>>n;
    x=0;
    i=0;
    while(x!=n)
    {
        long long j;
        i+=5;
        j=i;
        while(j%5==0)
        {
            x++;
            j/=5;
        }
    }
    g<<i;
    return 0;
}