#include <iostream>
#include <fstream>
using namespace std;
ifstream in("factorial.in");
ofstream out("factorial.out");
int main()
{
    int p;
    in>>p;
    if(p==0)
    {
        out<<"1";
        return 0;
    }
    for(long long i=5; ;i++)
    {
        int ci=i;
        while(ci%5==0)
        {
            p--;
            ci=ci/5;
        }
        if(p<=0)
        {
            out<<i;
            return 0;
        }
    }
    return 0;
}