#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;} template inline string toString(T x) {ostringstream sout;sout< VI; typedef vector VVI; typedef vector VS; typedef pair PII; typedef tuple TIII; typedef long long LL; typedef unsigned long long ULL; #define FOR(i,a,b) for(int i=(a);i<(b);++i) #define REP(i,n) FOR(i,0,n) #define MP make_pair #define MT make_tuple #define SZ(a) int((a).size()) #define EACH(i,c) for(auto i: c) #define SORT(c) sort((c).begin(),(c).end()) #define ALL(a) (a).begin(),(a).end() #define RALL(a) (a).rbegin(), (a).rend() const double EPS = 1e-10; const double PI = acos(-1.0); #define dump(x) cerr << #x << " = " << (x) << endl; #define debug(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ")" << " " << __FILE__ << endl; int main() { cin.tie(0); ios::sync_with_stdio(false); int D; cin >> D; int ret, l = 0; while((l + 1) * (l + 1) <= D) l++; ret = l; while(ret * 2 + (l + 1) * 2 <= D) l++; ret *= l; if(D < 4) ret = 0; cout << ret << endl; return 0; }