#include<iostream>
#include<fstream>
#include<vector>
using namespace std;
long long int n;
ifstream in("fact.in");
ofstream out("fact.out");
long long int nrcifr(long n)
{
    unsigned long long int f=0;
    for(long long int i=5;i<=n;i=i*i)
        f=n/i+f;
    return f;
}
int cauarebinara0(int k)
{
    long long int step=2<<27;
    long long int sol=0;
    for(; step>=1; step=step/2)
       if(nrcifr(step+sol)<k)
          sol=step+sol;
    return sol+1;
}
int main()
{
    cin>>n;
    cout<<cauarebinara0(n);

}