#include <bits/stdc++.h>
using namespace std;
#define task "main"
#define F first
#define S second
#define ii pair<int, int>
#define il pair<int, long long>
#define li pair<long long, int>
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
const int MAX_N = 65;
const int MOD = (int)1e9 + 7;
void add(int &x, int y) {
x += y;
if (x >= MOD) x -= MOD;
}
void sub(int &x, int y) {
x -= y;
if (x < 0) x += MOD;
}
int nNode, nPair, k;
vector<ii> adj[MAX_N];
ii magics[MAX_N];
int poww[MAX_N + 10];
long long edgeMask[20];
bool DFSPrepare(int u, int p, int dest, int pairID, long long edges) {
if (u == dest) {
edgeMask[pairID] = edges;
return true;
}
for (ii e : adj[u]) {
int v = e.F, id = e.S;
if (v == p) continue;
edges |= (1LL << id);
if (DFSPrepare(v, u, dest, pairID, edges))
return true;
edges ^= (1LL << id);
}
return false;
}
int valid[MAX_N];
bool DFSCom(int u, int p, int dest) {
valid[u]++;
if (u == dest) return true;
for (ii e : adj[u]) {
int v = e.F, id = e.S;
if (v == p) continue;
if (DFSCom(v, u, dest)) return true;
}
valid[u]--;
return false;
}
bool visited[MAX_N];
void DFS(int u, int p) {
visited[u] = 1;
for (ii e : adj[u]) {
int v = e.F, id = e.S;
if (v == p) continue;
if (valid[v]) DFS(v, u);
}
}
int calc(int mask) {
memset(valid, 0, sizeof(valid));
memset(visited, 0, sizeof(visited));
long long totalEdge = 0;
FOR(i, 0, nPair - 1) if (mask >> i & 1) {
DFSCom(magics[i + 1].F, -1, magics[i + 1].S);
totalEdge |= edgeMask[i + 1];
}
int nCom = 0, nEdge = nNode - 1 - __builtin_popcountll(totalEdge);
FOR(i, 1, nNode) if (!visited[i] && valid[i]) {
nCom++;
DFS(i, -1);
}
return poww[nCom + nEdge];
}
void solve() {
cin >> nNode >> nPair >> k;
FOR(i, 1, nNode - 1) {
int u, v;
cin >> u >> v;
adj[u].push_back({v, i - 1});
adj[v].push_back({u, i - 1});
}
FOR(i, 1, nPair) cin >> magics[i].F >> magics[i].S;
poww[0] = 1;
FOR(i, 1, nNode + 5) poww[i] = 1LL * poww[i - 1] * k % MOD;
FOR(i, 1, nPair) {
DFSPrepare(magics[i].F, -1, magics[i].S, i, 0);
}
int ans = poww[nNode - 1];
FOR(mask, 1, (1 << nPair) - 1) {
if (__builtin_popcount(mask) & 1)
sub(ans, calc(mask));
else
add(ans, calc(mask));
}
cout << ans;
}
int32_t main() {
if (fopen(task".inp", "r")) {
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
bool multitest = 0;
int numTest = 1;
if (multitest) cin >> numTest;
while (numTest--) {
solve();
}
return 0;
}
/* Lak lu theo dieu nhac!!!! */
