#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int ver(int n, int p)
{
    int a=0;
    while (n)
    {
        a+=n/5;
        n=n/5;
    }
    if(a==p)
    return 1;
    else
    if (a<p)
    return 0;
    if (a>p)
    return -1;
}

int main()
{
    int i=1,p,n;
    f>>p;
    if(p)
    {
        n=(4*p-((4*p)&5));
        while (i)
        {
            if(ver(n,p)==1)
            {g<<n-n%5; i=0;}
            if(ver(n,p)==-1)
            {g<<-1; i=0;}
            if(ver(n,p)==0)
            n+=5;
        }
    }
    else    g<<1;
return 0;
}