#include <bits/stdc++.h>

using namespace std;
ifstream in("fact.in");
ofstream out ("fact.out");
int p;
bool check(int val)
{
    int a=0,b=0,t;
    t=val;
    while(t>0)
    {
        t/=2;
        a+=t;
    }
    t=val;
    while(t>0)
    {
        t/=5;
        b+=t;
    }
    return min(a,b)<p;
}

int main()
{
    in>>p;
    int ans=0;
    for(int msk=1<<30;msk>0;msk/=2)
    ans+=msk*int(check(ans+msk));
    if(check(ans+1)!=p)
    out<<-1;
    else
    out<<ans+1;
    return 0;
}