#include <fstream>

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