#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fact.in");
ofstream o("fact.out");
int desc(int x)
{
    int e=0;
    while (x%5==0)
    {
         e=e+1;
         x=x/5;
    }
    return e;
}
int main()
{
    int p;
    f>>p;
    if(p==0)
        o<<1;
    else {


    int nr=0;
    int x=5;
    while(nr!=p)
    {
        nr=nr+desc(x);
        x=x+5;
    }
    o<<x-5;
    }

}