import java.util.Scanner;
import java.io.*;

public class Main {
    static int num5(int n){
        int k=0;
        while(n%5==0){
            n/=5;
            k++;
        }
        return k;
    }
    public static void main(String[] args) throws IOException {
        Scanner reader = new Scanner(new FileInputStream("fact.in"));
        PrintWriter writer = new PrintWriter("fact.out");
        int p = reader.nextInt();
        int i=0,n=0;
        if(p<0) writer.write("-1");
        if(p==0) writer.write("1");
        if(p>0){
        while(i<p){
            n+=5;
            i+=num5(n);
        }}
        if(i==p && p>0) writer.write(n+"\n");
        if(i!=p && p>0) writer.write("-1");
        reader.close();
        writer.close();
    }
}