#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
long long int s=1,x;
int main()
{
    int n,p,ct=0,i=1;;
    fin>>p;
    while(s>=1)
    {
        s=s*i;
        x=s;
        ct=0;
        while(x%10==0)
        {
            ct++;
            x=x/10;
        }
        if(ct==p)
        {

        break;
        }
        i++;
    }
fout<<" "<<i;
    return 0;
}