#include <fstream>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
int main()
{
unsigned cs,s,n=0,nr,p,k;
in>>p;
s=0;
while (s!=p) {
    n=n+5;
    s=s+1;
    nr=n;
    k=0;
    while (nr%5==0) {
        nr=nr/5;
        k++;
    }
    if (k>1)
        s=s+k-1;
}
if (s==0)
    n++;
out<<n;
    return 0;
}