#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    int x, nr, div, cz;
    in >> nr;
    x = cz = 0;
    while ( cz < nr ) {
        x += 5;
        div = x;
        while ( div % 5 == 0 ) {
            div /= 5;
            cz++;
        }
    }
    if ( x == 0 )
        out << 1;
    else
        out << x;
    return 0;
}