import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class Main {
	static List<List<Hen>> list;

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		String[] sa = br.readLine().split(" ");
		int n = Integer.parseInt(sa[0]);
		int m = Integer.parseInt(sa[1]);
		int x = Integer.parseInt(sa[2]);
		list = new ArrayList<>(n);
		for (int i = 0; i < n; i++) {
			list.add(new ArrayList<>());
		}
		UnionFind uf = new UnionFind(n);
		List<Hen> hens = new ArrayList<>();
		for (int i = 0; i < m; i++) {
			sa = br.readLine().split(" ");
			Hen h = new Hen();
			h.x = Integer.parseInt(sa[0]) - 1;
			h.y = Integer.parseInt(sa[1]) - 1;
			h.z = Integer.parseInt(sa[2]);
			if (!uf.same(h.x, h.y)) {
				uf.union(h.x, h.y);
				list.get(h.x).add(h);
				list.get(h.y).add(h);
				hens.add(h);
			}
		}
		br.close();

		dfs(0, -1);
		int mod = 1000000007;
		long ans = 0;
		for (Hen h : hens) {
			long cnt = (long) h.c * (n - h.c) % mod;
			ans += power(x, h.z, mod) * cnt;
			ans %= mod;
		}
		System.out.println(ans);
	}

	static int dfs(int cur, int p) {
		int ret = 1;
		List<Hen> nexts = list.get(cur);
		for (Hen h : nexts) {
			int next = h.x;
			if (next == cur) {
				next = h.y;
			}
			if (next == p) {
				continue;
			}
			h.c = dfs(next, cur);
			ret += h.c;
		}
		return ret;
	}

	static class Hen {
		int x, y, z, c;
	}

	static long power(long x, long n, int m) {
		if (n == 0) {
			return 1;
		}
		long val = power(x, n / 2, m);
		val = val * val % m;
		if (n % 2 == 1) {
			val = val * x % m;
		}
		return val;
	}

	static class UnionFind {
		int[] parent, size;
		int num = 0; // 連結成分の数

		UnionFind(int n) {
			parent = new int[n];
			size = new int[n];
			num = n;
			for (int i = 0; i < n; i++) {
				parent[i] = i;
				size[i] = 1;
			}
		}

		void union(int x, int y) {
			int px = find(x);
			int py = find(y);
			if (px != py) {
				parent[px] = py;
				size[py] += size[px];
				num--;
			}
		}

		int find(int x) {
			if (parent[x] == x) {
				return x;
			}
			parent[x] = find(parent[x]);
			return parent[x];
		}

		/**
		 * xとyが同一連結成分か
		 */
		boolean same(int x, int y) {
			return find(x) == find(y);
		}

		/**
		 * xを含む連結成分のサイズ
		 */
		int size(int x) {
			return size[find(x)];
		}
	}
}