#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
unsigned long int p;

int Caut(unsigned long long int a, unsigned long long int b)
{
    unsigned long long int mid, k, pw=0;
    mid = (a + b) / 2;
    k = mid;
    while (k % 5 == 0){
            k = k / 5;
            pw++;
        }
    if (pw == p){
        return mid;
    }
    else
    {
        if (mid == 0) return -1;
        if (pw < p)
            return Caut(mid+1,b);
        else return Caut(a,mid-1);
    }
}

main()
{
    ifstream f1("fact.in");
    ofstream f2("fact.out");
    f1>>p;
    if (p == 0) f2 << 1;
    f2 << Caut(0,pow(10,10));
}