#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool upmin(T &x, T y) {
  return y <= x ? x = y, 1 : 0;
}
template <typename T>
inline bool upmax(T &x, T y) {
  return x <= y ? x = y, 1 : 0;
}
const long double eps = 1e-9;
const long double pi = acos(-1);
const int oo = 1 << 30;
const long long loo = 1ll << 60;
const int MAXN = 300005;
const int MAXM = 4005;
const int MX = 200000;
const int G = 3;
const int mods = 998244353;
const int Gi = (mods + 1) / G;
const int SZ = 62;
const int inv2 = (mods + 1) >> 1;
const int INF = 0x3f3f3f3f;
namespace FastIO {
constexpr int SIZE = (1 << 21) + 1;
int num = 0, f;
char ibuf[SIZE], obuf[SIZE], que[65], *iS, *iT, *oS = obuf,
                                                *oT = obuf + SIZE - 1, c;
inline void flush() {
  fwrite(obuf, 1, oS - obuf, stdout);
  oS = obuf;
}
inline void putc(char c) {
  *oS++ = c;
  if (oS == oT) flush();
}
inline void getc(char &c) {
  for (c = (iS == iT ? (iT = ((iS = ibuf) + fread(ibuf, 1, SIZE, stdin)),
                       (iS == iT ? EOF : *iS++))
                     : *iS++);
       !isalpha(c) && c != EOF;
       c = (iS == iT ? (iT = ((iS = ibuf) + fread(ibuf, 1, SIZE, stdin)),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    ;
}
inline void reads(char *st) {
  char c;
  int n = 0;
  getc(st[++n]);
  for (c = (iS == iT ? (iT = ((iS = ibuf) + fread(ibuf, 1, SIZE, stdin)),
                       (iS == iT ? EOF : *iS++))
                     : *iS++);
       isalpha(c);
       c = (iS == iT ? (iT = ((iS = ibuf) + fread(ibuf, 1, SIZE, stdin)),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    st[++n] = c;
  st[++n] = '\0';
}
template <class I>
inline void read(I &x) {
  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;
  for (x = 0; c >= '0' && c <= '9';
       c = (iS == iT ? (iT = ((iS = ibuf) + fread(ibuf, 1, SIZE, stdin)),
                       (iS == iT ? EOF : *iS++))
                     : *iS++))
    x = (x << 3) + (x << 1) + (c & 15);
  x *= f;
}
template <class I>
inline void print(I x) {
  if (x < 0) putc('-'), x = -x;
  if (!x) putc('0');
  while (x) que[++num] = x % 10 + 48, x /= 10;
  while (num) putc(que[num--]);
}
inline void putstr(string st) {
  for (int i = 0; i < (int)st.size(); ++i) putc(st[i]);
}
struct Flusher_ {
  ~Flusher_() { flush(); }
} io_Flusher_;
}  // namespace FastIO
using FastIO ::getc;
using FastIO ::print;
using FastIO ::putc;
using FastIO ::putstr;
using FastIO ::read;
using FastIO ::reads;
long long g[MAXN][3];
vector<int> e[MAXN];
void tree_dp(int x, int father) {
  int num = 0;
  for (auto v : e[x]) {
    if (v == father) continue;
    tree_dp(v, x);
    ++num;
  }
  if (!num) {
    g[x][0] = g[x][2] = 1;
    return;
  }
  g[x][0] = g[x][1] = g[x][2] = 1;
  for (auto v : e[x]) {
    if (v == father) continue;
    g[x][2] = g[x][2] * (g[v][0] + g[v][1]) % mods;
    g[x][1] = g[x][1] * (g[v][0] + g[v][0] + g[v][1]) % mods;
    g[x][0] =
        g[x][0] * (g[v][0] + g[v][0] + g[v][1] + g[v][1] + g[v][2]) % mods;
  }
  g[x][1] = (g[x][1] + mods - g[x][2]) % mods;
}
signed main() {
  int n;
  read(n);
  for (int i = 1, u, v; i < n; ++i)
    read(u), read(v), e[u].push_back(v), e[v].push_back(u);
  tree_dp(1, 0);
  print((g[1][0] + g[1][1] - 1) % mods);
  return 0;
}
