#include<fstream>
#include<iostream>
using namespace std;
long nrzero(long n){
     long nr=0;
     while(n>1){
         nr+=n/5; 
         n=n/5;
     }
     return nr;
}

long p;
long factorial(long l, long r){
     long m=(l+r)/2;
     long nm=nrzero(m);
    
     if(nm==p)
         return m;
     if(nm>p)
         return factorial(l,m-1);
     return factorial(m+1, r);    
}         


int main(){
    ifstream f("fact.in");
    ofstream g("fact.out");
    f>>p;
    cout<<p;
    if(p==0)
        g<<1;
    else    
       g<<factorial(1,100000000)/5*5; 
   
    f.close();
    g.close();   
    return 0;
}