#include <iostream>
#include <fstream>

using namespace std;

unsigned long long nr_de_5(int n) {
    unsigned long long rez=0;
    while(n%5==0){
        rez++;
        n=n/5;
    }
    return rez;
}


int main() {
    ifstream f("fact.in");
    ofstream g("fact.out");
    unsigned long long p;
    f>>p;
    if(p==0) {
        g<<1;
    }else{
        unsigned long long i=5,rez=1;
        while(rez<p) {
            i=i+5;
            rez=rez+nr_de_5(i);
        }
        if(p==rez){
            g<<i;
        }else{
            g<<-1;
        }
    }
    f.close();
    g.close();
}