n=int(input())
if n%2:print(0)
else:
d=n//2
if d%2:print(d//2)
else:print(d//2-1)#include<bits/stdc++.h>
using namespace std;
int main()
{
long long int n;
cin>>n;
if(n%2!=0){
cout<<0;
return 0;
}
if(n%2==0){
int a=n/2;
if(a%2==0){
a=(a/2)-1;
}
else{
a=a/2;
}
cout<<a;
}
return 0;
}706B - Interesting drink | 1265A - Beautiful String |
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