#include <bits/stdc++.h>
using namespace std;
int inf;
const double eps = 1e-8;
const double pi = acos(-1.0);
template <class T>
int chkmin(T &a, T b) {
  return a > b ? a = b, 1 : 0;
}
template <class T>
int chkmax(T &a, T b) {
  return a < b ? a = b, 1 : 0;
}
template <class T>
T sqr(T a) {
  return a * a;
}
template <class T>
T mmin(T a, T b) {
  return a < b ? a : b;
}
template <class T>
T mmax(T a, T b) {
  return a > b ? a : b;
}
template <class T>
T aabs(T a) {
  return a < 0 ? -a : a;
}
template <class T>
int dcmp(T a, T b) {
  return a > b;
}
template <int *a>
int cmp_a(int first, int second) {
  return a[first] < a[second];
}
struct __INIT__ {
  __INIT__() { memset(&inf, 0x3f, sizeof(inf)); }
} __INIT___;
namespace io {
const int SIZE = (1 << 21) + 1;
char ibuf[SIZE], *iS, *iT, obuf[SIZE], *oS = obuf, *oT = oS + SIZE - 1, c,
                                       qu[55];
int f, qr;
inline void flush() {
  fwrite(obuf, 1, oS - obuf, stdout);
  oS = obuf;
}
inline void putc(char first) {
  *oS++ = first;
  if (oS == oT) flush();
}
inline bool read(signed &first) {
  for (f = 1, c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                              (iS == iT ? EOF : *iS++))
                            : *iS++);
       c < '0' || c > '9';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    if (c == '-')
      f = -1;
    else if (c == EOF)
      return 0;
  for (first = 0; c <= '9' && c >= '0';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    first = first * 10 + (c & 15);
  first *= f;
  return 1;
}
inline bool read(long long &first) {
  for (f = 1, c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                              (iS == iT ? EOF : *iS++))
                            : *iS++);
       c < '0' || c > '9';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    if (c == '-')
      f = -1;
    else if (c == EOF)
      return 0;
  for (first = 0; c <= '9' && c >= '0';
       c = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    first = first * 10 + (c & 15);
  first *= f;
  return 1;
}
inline bool read(char &first) {
  first = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                       (iS == iT ? EOF : *iS++))
                    : *iS++);
  return first != EOF;
}
inline bool read(char *first) {
  while ((*first = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                                (iS == iT ? EOF : *iS++))
                             : *iS++)) == '\n' ||
         *first == ' ' || *first == '\r')
    if (*first == EOF) return 0;
  while (!(*first == '\n' || *first == ' ' || *first == '\r'))
    *(++first) = (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin),
                              (iS == iT ? EOF : *iS++))
                           : *iS++);
  *first = 0;
  return 1;
}
template <typename A, typename... B>
inline bool read(A &first, B &...second) {
  return read(first) && read(second...);
}
inline bool write(signed first) {
  if (!first) putc('0');
  if (first < 0) putc('-'), first = -first;
  while (first) qu[++qr] = first % 10 + '0', first /= 10;
  while (qr) putc(qu[qr--]);
  return 0;
}
inline bool write(long long first) {
  if (!first) putc('0');
  if (first < 0) putc('-'), first = -first;
  while (first) qu[++qr] = first % 10 + '0', first /= 10;
  while (qr) putc(qu[qr--]);
  return 0;
}
inline bool write(char first) {
  putc(first);
  return 0;
}
inline bool write(const char *first) {
  while (*first) {
    putc(*first);
    ++first;
  }
  return 0;
}
inline bool write(char *first) {
  while (*first) {
    putc(*first);
    ++first;
  }
  return 0;
}
template <typename A, typename... B>
inline bool write(A first, B... second) {
  return write(first) || write(second...);
}
struct Flusher_ {
  ~Flusher_() { flush(); }
} io_flusher_;
}  // namespace io
using io ::putc;
using io ::read;
using io ::write;
int n, m;
vector<int> ans, to[1 << 17 | 5];
int ok, is;
int siz[1 << 17 | 5];
int cnt[1 << 17 | 5];
bool isbinary(int dp, int first, int f) {
  if (!dp) return 0;
  if (dp == 1) return to[first].size() == 1;
  if (to[first].size() != 3) return 0;
  for (auto i : to[first])
    if (i != f)
      if (!isbinary(dp - 1, i, first)) return 0;
  return 1;
}
void getsize(int first, int f) {
  cnt[first] = 1;
  for (auto i : to[first])
    if (i != f) {
      getsize(i, first);
      cnt[first] += cnt[i];
    }
}
void dfs(int dp, int first, int f, bool ntrt = 0) {
  if (!ok) return;
  if (dp == 1) {
    if (to[first].size() != ntrt) {
      ok = 0;
    }
    return;
  }
  if (to[first].size() - ntrt > 3) {
    ok = 0;
    return;
  }
  if (to[first].size() - ntrt == 3) {
    if (~is) {
      ok = 0;
      return;
    }
    int mx = 0, xs = 0, at = 0;
    for (auto i : to[first])
      if (i != f) {
        if (chkmax(mx, cnt[i])) at = i;
        xs ^= cnt[i];
      }
    if (!ntrt) {
      if (xs) {
        ok = 0;
        return;
      }
      for (auto i : to[first])
        if (i != f)
          if (!isbinary(dp - 2, i, first)) {
            ok = 0;
            return;
          }
      is = first;
      return;
    } else {
      if (mx != xs) {
        ok = 0;
        return;
      }
      for (auto i : to[first])
        if (i != f) {
          if (!isbinary(dp - 2 + (i == at), i, first)) {
            ok = 0;
            return;
          }
        }
      is = first;
      return;
    }
  }
  if (to[first].size() - ntrt == 1) {
    if (dp == 2) {
      for (auto i : to[first])
        if (i != f) {
          if (cnt[i] != 1) {
            ok = 0;
            return;
          }
        }
      is = first;
      return;
    } else {
      ok = 0;
      return;
    }
  }
  for (auto i : to[first])
    if (i != f) dfs(dp - 1, i, first, 1);
}
void check(int rt, int mxs) {
  getsize(rt, 0);
  if (!isbinary(n - 1, mxs, rt)) return;
  ok = 1;
  is = -1;
  dfs(n, rt, mxs);
  if (!ok || !~is) return;
  ans.push_back(is);
}
void dfs(int first, int f) {
  siz[first] = 1;
  for (auto i : to[first])
    if (i != f) {
      dfs(i, first);
      if (siz[i] << 1 == m) {
        check(first, i);
        check(i, first);
      }
      siz[first] += siz[i];
    }
}
signed main() {
  read(n);
  if (n == 2) return write("2\n1 2\n");
  m = (1 << n) - 2;
  for (int i = 1; i < m; ++i) {
    int u, v;
    read(u, v);
    to[u].push_back(v);
    to[v].push_back(u);
  }
  dfs(1, 0);
  sort(ans.begin(), ans.end());
  write((int)ans.size(), '\n');
  for (auto i : ans) write(i, ' ');
  write('\n');
  return 0;
}
