#include <stdio.h>
#include <stdlib.h>
#include <iostream>
#include <fstream>
using namespace std;
int main(){
    int p,i=1,S=0,b;
    ifstream in("fact.in");
    ofstream out("fact.out");
    in>>p;
    //printf("Tastati p=");
    scanf("%d",&p);
    while(p!=S){
           b=i;
           i++;
          while(b%5==0){

          b=b/5;
          S=S+1;
          if(p==S) break;

        }





    }

out<<i<<"\n";
in.close();
    out.close();
   // printf("Valoarea lui n este egala cu:%d",i);
return 0;




}