#include <iostream>
#include <fstream>

using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");

int main() {
    int P,N=-1,i,numar,zero = 0;
    fin>>P;

    for (i=1;i<=1000000;i++){
        numar=i;
        while(numar%5==0){
            zero++;
            numar/=5;
        }
        if(zero==P){
            N=i;
            break;
    }   }
    fout<<N<<endl;
    fin.close();
    fout.close();
    return 0;
}