#include <iostream>
#include <fstream>


using namespace std;

void randuri();
void coloane();


ifstream fin("fact.in");
ofstream fout("fact.out");



int main()
{
    long long int p,k,i,j;

    fin>>p;
    if(p==0){
        fout<<"1";
        return 0;
    }
    k=0;

    for(i=5;k<p;i+=5){
        k++;
        j=i/5;
        while(j%5==0){
            k++;
            j/=5;
        }
    }
    i-=5;
    fout<<i;
}