#include <fstream>

using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int P;
int main()
{
    int pas = 1 << 30, i = 1;
    cin >> P;
    while(pas)
    {
        int ps = i + pas, nrz = 0;
        while(ps > 1)
        {
            nrz += ps / 5;
            ps /= 5;
        }
        if(nrz <= P - 1) i += pas;
        pas /= 2;
    }
    cout << i + 1;
    return 0;
}