///infoarena problema factorial
#include <bits/stdc++.h>

using namespace std;
int nrz,k,nrcrt,temp;
ifstream fin("fact.in");
ofstream fout("fact.out");
int main()
{
    fin >> k;
    if(k==0)
    {
        fout<< 1;    ///tratam cazul particular cand K=0
        return 0;
    }
    nrcrt=5;
    nrz=1;                    ///pt nr 5! avem 1 zero
    while(k>nrz)
    {

        nrcrt=nrcrt+5;
        temp=nrcrt;
        while(temp%5==0)
        {
            nrz=nrz+1;
            temp=temp/5;

        }
    }
    if(nrz==k)
        fout<< nrcrt;
    else
     fout<< -1;



    return 0;
}