#include <iostream>
#include <fstream>
using namespace std;

int p, zero = 0;

int main() {
    ifstream f("fact.in");
    ofstream g("fact.out");
    f >> p;
    if(p == 0)
        g << 1;
    else {
        int n = p * 5;
        int cinci = 5;
        while(cinci <= n) {
            zero += n/cinci;
            cinci *= 5;
        }

        while(zero > p) {
            int c = n;
            while(c % 5 == 0) {
                c /= 5;
                zero--;
            }
            n -= 5;
        }
        if(zero == p)
            g << n;
        else
            g << -1;
    }

    f.close();
    g.close();
    return 0;
}