#include <fstream>
#include <algorithm>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

long long n, nr, x, p, i;
bool ok;

int main()
{   f >> n;
    for ( i = 5; i <= 5000000; i = i + 5 ){
        x = i;
        p = 0;
        while ( x % 5 == 0 ){
            p++;
            x = x / 5;
        }
        nr = nr + p;
        if ( nr == n ){
            break;
            ok = true;
        }
        else if ( nr > n ){
            break;
            ok = false;
        }
    }
    if ( n == 0 )
        g << "1";
    else if ( ok == true )
        g << i;
    else
        g << "-1";



    return 0;
}