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#include<bits/stdc++.h>
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#define int long long
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const int mod = 998244353;
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const int N = 510;
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using namespace std;
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int n, m;
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int head[N], nxt[N << 1], to[N << 1], cnt = 1;
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int siz[N];
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unsigned long long hsh[N];
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int sum[N];
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void add(int x, int y)
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{
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  to[++cnt] = y;
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  nxt[cnt] = head[x];
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  head[x] = cnt;
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}
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void dfs1(int u, int fa)
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{
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//
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  for(int i = head[u]; i; i = nxt[i])
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  {
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    int v = to[i];
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    if(v == fa) continue;
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    dfs1(v, u);
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    siz[u] += siz[v];
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  }
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//  cout << " " <<u << " " << siz[u] << endl;
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}
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void dfs2(int u, int fa)
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{
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  hsh[u] = siz[u] + 10;
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  for(int i = head[u]; i; i = nxt[i])
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  {
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    int v = to[i];
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    if(v == fa) continue;
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    dfs2(v, u);
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    hsh[u] *= ((hsh[v] * 114 + 4869) * (hsh[v] * 114 + 4869) - 100);
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  }
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  hsh[u] -= 4869;
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//  cout << " " <<u << " " << siz[u] << endl;
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}
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int ksm(int a, int n)
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{
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  if(a == 1) return 1;
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  int ans = 1;
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  while(n)
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  {
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    if(n & 1) ans = ans * a % mod;
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    a = a * a % mod;
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    n >>= 1;
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  }
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  return ans;
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}
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void dfs3(int u, int fa)
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{
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  sum[u] = m;
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  unordered_map<unsigned long long, int> cnt;
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  for(int i = head[u]; i; i = nxt[i])
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  {
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    int v = to[i];
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    if(v == fa) continue;
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    dfs3(v, u);
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  }
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  for(int i = head[u]; i; i = nxt[i])
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  {
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    int v = to[i];
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    if(v == fa) continue;
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    sum[u] = (sum[u] * (sum[v] + cnt[hsh[v]]) % mod) * ksm(cnt[hsh[v]] + 1, mod - 2) % mod;
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    cnt[hsh[v]] ++;
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  }
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//  cout << u << " "  << sum[u] << endl;
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}
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signed main()
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{
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  scanf("%lld%lld", &n, &m);
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  for(int i = 1;i <= n;i++)
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    siz[i] = 1;
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  int u, v;
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  for(int i = 1;i <= n - 1;i++)
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  {
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    cin >> u >> v;
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//    cout << "qwq" << u << " " << v << endl;
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    add(u, v), add(v, u);
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  }
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  dfs1(1, 0);
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  dfs2(1, 0);
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  dfs3(1, 0);
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  printf("%lld\n", sum[1]);
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  return 0;
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}