#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

int n, f[200010], vis[200010];
ll k, dp[3][200010], ret, c;
const ll mod = 998244353;
vector<int>a[200010];

void dfs(int u, int pre)
{
    vis[u] = 1;
    for (int v : a[u]) if (v != pre)
    {
        if (vis[v]) c = abs(f[v] - f[u]) + 1;
        else f[v] = f[u] + 1, dfs(v, u);
    }
}

int main()
{
    cin >> n >> k;
    for (int i=1; i<=n; i++)
    {
        int x, y;
        cin >> x >> y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    dfs(1, 0);
    dp[1][1] = k;
    for (int i=2; i<=c; i++)
    {
        dp[1][i] = dp[2][i-1];
        dp[2][i] = (dp[1][i-1] * (k-1) + dp[2][i-1] * (k-2)) % mod;
    }
    ret = dp[2][c];
    for (int i=1; i<=n-c; i++) ret = (ret * (k-1)) % mod;
    cout << ret;
}