#include <iostream>
#include <fstream>
 
using namespace std;
 
ifstream fin("fact.in");
ofstream fout("fact.out");
 
int n;
 
int z(int x)
{
    int i,k;
    k=0;
    for(i=5;i<=x;i*=5)
        k+=x/i;
    return k;
}
 
int cauta(int st, int dr)
{
    int m,x;
    while(st<=dr)
    {
        m=(st+dr)/2;
        x=z(m);
        if(x==n)
            return m;
        if(n>x)
            st+=m;
        else
            dr-=m;
    }
}
 
int main()
{
    fin>>n;
    int i;
    i=cauta(1,1000000000);
    while(i%5!=0)
        i--;
    if(n==0)
        i=1;
    if(z(i) == n)
        fout<<i<<"\n";
    else
        fout<<-1<<"\n";
    fin.close();
    fout.close();
    return 0;
}