#include<iostream>
#include<fstream>
#include<climits>
using namespace std;
 
ifstream fin("fact.in");
ofstream fout("fact.out");
 
int main(){
    int p,m,i=1,k,j=LONG_MAX,ok=0,x;
    fin>>p;
    if(p==0)fout<<"1";
    while(i<=j&&ok==0){
        m=(i+j)/2;
        x=5;k=0;
        while(x<=m){k=k+m/x;
                    x=x*5;}
        if(k==p)ok=1;
           else if(k>p)j=m-1;
                else i=m+1;
    }
    if(ok==0)fout<<"-1";
       else {while(m%5!=0)m--;
             fout<<m;}
 
 
    fin.close();
    fin.close();
    return 0;
}