#include <fstream>
#include <stdio.h>
using namespace std;
int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    unsigned long long n,p;
    f>>p;
    unsigned long long i=1,nr2=0,nr5=0;
    while(i>=1)
    {
        unsigned long long i1=i,minx;
        if(i1%2==0) while (i1%2==0) {i1=i1/2; nr2++;}
        if (i1%5==0) while (i1%5==0) {i1=i1/5; nr5++;}
        if (min(nr5,nr2)==p) break;
        i++;
    }
    g<<i;
}