#include <iostream>
#include <fstream>

using namespace std;
ifstream f ( "fact.in" ) ;
ofstream g ( "fact.out" ) ;
int p, n = 0, m , k = 1 ;
int main()
{
    f >> p ;
    if ( p == 0 )
        g << 1 ;
    else
    {
        while ( p > 0 )
        {
            n += 5 ;
            if ( n >= 25 * k )
            {
                p -= 2 ;
                k ++ ;
            }
            else
                p -- ;
        }
    }
    if ( p == 0 )
        g << n ;
    else
        g << - 1 ;
    return 0;
}