#include<fstream>
using namespace std;
int main()
{
    int i1,n,m5=0,i=5;
    ifstream fin ("fact.in");
    ofstream fout ("fact.out");
    fin>>n;

        while(i1!=0)
        {
            i1=i;
            i1=i1/5;
            m5++;


        if(n==m5)
        {
            fout<<i;
            break;
        }
        i+=5;
        }
    }