#include <fstream>

using namespace std;


ifstream in("fact.in");
ofstream out("fact.out");
int nr0 (int p)
{
    int i=0;
    while(p)
    {
        i=i+p/5;
        p=p/5;
    }
    return i;
}

int main()
{
    int p,a;
    in>>p;
    for(a=1;  a<=5*p;  a=a*2){
    }
    int sol=5*p+1;
    for( int step=a;  step>0;  step/=2)
    {
        if(sol-step>0 && nr0(sol-step)>=p)
        sol-=step;
    }
    if(nr0(sol)==p)
    out<<sol;
    else
    out<<-1;
    return 0;
}