#include <iostream>

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