#include<fstream.h>
#define input "fact.in"
#define output "fact.out"

int main()
    {
    int n,k,i,h;
    ifstream fin(input);
    ofstream fout(output);
    fin>>n;
    k=0;
    for(i=5;k<n;i=i+5)
        {
        k++;
      h=i/5;
        while(h%5==0)
            {
            k++;
            h=h/5;
            }
        }
    fout<<i-5;
    return 0;
    }