#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main()
{int P,d=0,c=0,t;
long long i;
in>>P;

    for(i=2;i<=LONG_MAX;i++)
    if (d<P || c<P)
    {t=i;
        while(t%2==0)
    {d++;
    t=t/2;}
while(t%5==0)
{t=t/5;
    c++;}}
    else
        break;
out<<i-1;
    return 0;
}