#include <iostream>
#include <vector>
#include <atcoder/dsu>
#include <atcoder/modint>

using mint = atcoder::modint998244353;

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);

    int n, k;
    std::cin >> n >> k;

    std::vector<std::vector<int>> g(n);

    atcoder::dsu uf(n);
    int x = -1, y = -1;
    for (int i = 0; i < n; ++i) {
        int u, v;
        std::cin >> u >> v;
        --u, --v;
        if (uf.same(u, v)) {
            x = u, y = v;
        } else {
            g[u].push_back(v);
            g[v].push_back(u);
            uf.merge(u, v);
        }
    }

    std::vector<int> d(n);
    auto dfs = [&](auto dfs, int u, int p) -> void { for (int v : g[u]) if (v != p) d[v] = d[u] + 1, dfs(dfs, v, u); };
    dfs(dfs, x, -1);
    int t = d[y] + 1;

    mint a = mint(k - 1).pow(n), b = mint(k - 1).pow(n - t + 1);
    std::cout << (t % 2 ? a - b : a + b).val() << std::endl;
}