#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
 
using namespace std;
 
ifstream in("fact.in");
ofstream out("fact.out");
//int NMAX = 1000000000;
 
int f( int x ){
 
    int rez = 0;
    int a = 5;
    while(1){
        rez += x/a;
        if( x/a == 0 )
            break;
        a *= 5;
    }
     
    return rez;
 
}
 
 
 
int main(){
 
    int p;
    in >> p;
     
    int left = 1, right = 1000000000, mid, temp, rez = -1;
     
     
    cout<< f(1000) <<endl;
    while( left <= right ){
     
        mid = left + (right-left)/2;
        temp = f(mid);
         
        if( temp == p ){
            rez = mid;
            break;
        }
        else if( temp < p )
            left = mid + 1;
        else
            right = mid - 1;
     
    }
    if(rez != -1)
        while( rez%5 != 0 ) rez--;
    if(p==0)
        rez = 1;
         
    out<<rez<<endl;
     
    return 0;
     
}