#include <iostream>
#include <iostream>
#include <cstdio>
using namespace std;
int factorial[1000];
int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    int p;cin>>p;
    if(p==5||((p/5)%5==0)&&p>5)
        cout<<"-1";
    else
    {
        int ans=5*p;
        for(int i=p;i>=0;i--)
            if(i==5||((i/5)%5==0)&&i>5)
                ans-=5;
        cout<<ans;
    }
    return 0;
}