#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream in("fact.in");
    ofstream out("fact.out");
    int p,x=1,nr2=0,nr5=0,ok=0,a;
    in>>p;
    while(ok==0)
    {
        a=x;
        while(a%5==0)
        {
            nr5++;
            a=a/5;
        }

        while(a%2==0)
        {
            nr2++;
            a=a/2;
        }
        if(nr2>=p && nr5>=p)
            ok=1;
        x++;
    }
    out<<x-1;
    return 0;
}