#include <fstream>

using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main()
{
    int i = 5, p, cnt = 1, putere = 1, cntm;

    in>>p;

    while(cnt<p) {
        cntm = cnt;
        i = i * 5;
        putere++;
        cnt += (i - i/5)/5 - 1 + putere;
    }

    if(p == cnt) { out<<i; return 0; }

    if(cnt - putere - (i - i/5)/5 + 1 < p && p <= cnt - putere) { out<<i/5 + (p - cntm) * 5; return 0; }

    out<<"-1";

    return 0;
}