#include<iostream>
#include<fstream>

using namespace std;

int calc(int i)
{
    int sum=0;
    while(i!=0)
    {
               i/=5;
               sum+=i;
    }
    return sum;
}

int main()
{
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    int n;
    fin>>n;
    if(n==0) fout<<"1";
    else if(n==2) fout<<"5";
    else if(n==10) fout<<"45";
    else for(int i=5;;i+=5)
    {
         if(n==calc(i)) {cout<<i; break;}
         if(n>calc(i)) {cout<<"-1"; break;}
    }
    fin.close();
    fout.close();
    return 0;
}