import java.io.*;
import java.util.*;

public class Main {
    static ArrayList<ArrayList<Path>> graph = new ArrayList<>();
    static final int MOD = 1000000007;
    static int n;
    static int base;
    static long ans = 0;
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        n = sc.nextInt();
        int m = sc.nextInt();
        base = sc.nextInt();
        for (int i = 0; i < n; i++) {
            graph.add(new ArrayList<>());
        }
        UnionFindTree uft = new UnionFindTree(n);
        for (int i = 0; i < m; i++) {
            int a = sc.nextInt() - 1;
            int b = sc.nextInt() - 1;
            int c = sc.nextInt();
            if (!uft.same(a, b)) {
                uft.unite(a, b);
                graph.get(a).add(new Path(b, c));
                graph.get(b).add(new Path(a, c));
            }
        }
        getCount(0, 0);
        System.out.println(ans);
    }
    
    static int getCount(int idx, int p) {
        int count = 1;
        for (Path x : graph.get(idx)) {
            if (x.idx == p) {
                continue;
            }
            int tmp = getCount(x.idx, idx);
            ans += (long)tmp * (n - tmp) % MOD * pow(base, x.value) % MOD;
            ans %= MOD;
            count += tmp;
        }
        return count;
    }
    
    static long pow(long x, int p) {
        if (p == 0) {
            return 1;
        } else if (p % 2 == 0) {
            return pow(x * x % MOD, p / 2);
        } else {
            return pow(x, p - 1) * x % MOD;
        }
    }
    
    static class UnionFindTree {
        int[] parents;
        
        public UnionFindTree(int size) {
            parents = new int[size];
            for (int i = 0; i < size; i++) {
                parents[i] = i;
            }
        }
        
        public int find(int x) {
            if (x == parents[x]) {
                return x;
            } else {
                return parents[x] = find(parents[x]);
            }
        }
        
        public boolean same(int x, int y) {
            return find(x) == find(y);
        }
        
        public void unite(int x, int y) {
            parents[find(x)] = find(y);
        }
    }
    
    static class Path {
        int idx;
        int value;
        
        public Path(int idx, int value) {
            this.idx = idx;
            this.value = value;
        }
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}