#include <iostream>
#include <fstream>

#define in ifstream("fact.in")
#define out ofstream("fact.out")

using namespace std;

int main(){
    int n = 0, p = 0, z = 0;
    in >> p;
    long long f;
    if(p == 0){
        out << 1 << endl;
    } else {
        n = 4 * p;
        n = n - n%5;
        f = 5;
        while(f <= n){
            z = z + n / f;
            f *= 5;
        }
    }

    while(!(z >= p)){
        if(z < p){
            n += 5;
        }

        f = n;

        while(f % 5 == 0){
            ++z;
            f /= 5;
        }
    }

    if(z == p){
        out << n << endl;
    } else {
        out << -1 << endl;
    }

}