#include <iostream>

using namespace std;

const int L=28;

int n, m;

int nr_zero(int n){
    int nr=0;
    while(n>=5){
        nr+=n/5;
        n/=5;
    }
    return nr;
}

int main()
{
    int r=0, pas=1<<L, p;
    cin >> p;
	while(pas!=0){
        if(nr_zero(r+pas)<p){
            r+=pas;
        }
        pas/=2;
	}
	r++;
	if(nr_zero(r)>p){
        r=-1;
	}
	cout << r;

    return 0;
}