#include<fstream>

using namespace std;

int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    int n,p,x;
    n = 1;
    f>>p;
    while(p > 0){
     n+=5;
     if(n == 6)
      n--;
     x = n;
     while(x % 5 == 0){
      p--;
      x = x / 5;
     }
    }
    if(p < 0)
     g<<-1;
    else
     g<<n;
    return 0;
}