Problem p03660 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for (ll i = (a); i > (b); --i)
#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOREACH(x, a) for (auto &(x) : (a))
#define VECCIN(x)                                                              \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define bitcnt __builtin_popcount
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()
template <typename T = long long> inline T IN() {
  T x;
  cin >> x;
  return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&...tail) {
  cin >> head;
  CIN(move(tail)...);
}
#define CCIN(...)                                                              \
  char __VA_ARGS__;                                                            \
  CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
  double __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
  ll __VA_ARGS__;                                                              \
  CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
  string __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define Printv(v)                                                              \
  {                                                                            \
    REP(x, v.size()) { cout << v[x] << (x == v.size() - 1 ? "\n" : " "); }     \
  }
template <typename T = string> inline void eputs(T s) {
  cout << s << "\n";
  exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}
template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<double> VD;

const int INF = 1e9;
const int MOD = 1e9 + 7;
const ll LINF = 1e18;
const ll dx[] = {1, 0, -1, 0};
const ll dy[] = {0, 1, 0, -1};
#define PI 3.141592653589793238

ll par[100000], dp[100000], dist, N;
VVL G(100);

ll dfs(ll now, ll pre, ll depth) {
  ll &res = dp[now];
  if (now == N - 1)
    dist = depth;
  par[now] = pre;
  FOREACH(to, G[now]) {
    if (to == pre)
      continue;
    dfs(to, now, depth + 1);
    dp[now] += dp[to];
  }
  return ++res;
}

signed main() {
  cin >> N;
  REP(i, N - 1) {
    LCIN(a, b);
    a--, b--;
    G[a].emplace_back(b);
    G[b].emplace_back(a);
  }
  dfs(0, -1, 0);
  ll v = N - 1;
  REP(loop, (dist - 1) / 2) v = par[v];
  cout << (dp[0] - dp[v] > dp[v] ? "Fennec" : "Snuke") << "\n";
}


Fixed submission:
#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define double long double
#define FOR(i, a, b) for (ll i = (a); i < (b); ++i)
#define FORR(i, a, b) for (ll i = (a); i > (b); --i)
#define REP(i, n) for (ll i = 0; i < (n); ++i)
#define REPR(i, n) for (ll i = n; i >= 0; i--)
#define FOREACH(x, a) for (auto &(x) : (a))
#define VECCIN(x)                                                              \
  for (auto &youso_ : (x))                                                     \
  cin >> youso_
#define bitcnt __builtin_popcount
#define SZ(x) ((ll)(x).size())
#define fi first
#define se second
#define All(a) (a).begin(), (a).end()
#define rAll(a) (a).rbegin(), (a).rend()
template <typename T = long long> inline T IN() {
  T x;
  cin >> x;
  return (x);
}
inline void CIN() {}
template <class Head, class... Tail>
inline void CIN(Head &&head, Tail &&...tail) {
  cin >> head;
  CIN(move(tail)...);
}
#define CCIN(...)                                                              \
  char __VA_ARGS__;                                                            \
  CIN(__VA_ARGS__)
#define DCIN(...)                                                              \
  double __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define LCIN(...)                                                              \
  ll __VA_ARGS__;                                                              \
  CIN(__VA_ARGS__)
#define SCIN(...)                                                              \
  string __VA_ARGS__;                                                          \
  CIN(__VA_ARGS__)
#define Printv(v)                                                              \
  {                                                                            \
    REP(x, v.size()) { cout << v[x] << (x == v.size() - 1 ? "\n" : " "); }     \
  }
template <typename T = string> inline void eputs(T s) {
  cout << s << "\n";
  exit(0);
}
template <typename A, size_t N, typename T>
void Fill(A (&array)[N], const T &val) {
  std::fill((T *)array, (T *)(array + N), val);
}
template <typename T> using PQG = priority_queue<T, vector<T>, greater<T>>;
template <typename T> using PQ = priority_queue<T>;

typedef long long ll;
typedef pair<ll, ll> PL;
typedef vector<PL> VPL;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef vector<double> VD;

const int INF = 1e9;
const int MOD = 1e9 + 7;
const ll LINF = 1e18;
const ll dx[] = {1, 0, -1, 0};
const ll dy[] = {0, 1, 0, -1};
#define PI 3.141592653589793238

ll par[100000], dp[100000], dist, N;
VVL G(100000);

ll dfs(ll now, ll pre, ll depth) {
  ll &res = dp[now];
  if (now == N - 1)
    dist = depth;
  par[now] = pre;
  FOREACH(to, G[now]) {
    if (to == pre)
      continue;
    dfs(to, now, depth + 1);
    dp[now] += dp[to];
  }
  return ++res;
}

signed main() {
  cin >> N;
  REP(i, N - 1) {
    LCIN(a, b);
    a--, b--;
    G[a].emplace_back(b);
    G[b].emplace_back(a);
  }
  dfs(0, -1, 0);
  ll v = N - 1;
  REP(loop, (dist - 1) / 2) v = par[v];
  cout << (dp[0] - dp[v] > dp[v] ? "Fennec" : "Snuke") << "\n";
}