#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC optimize("conserve-stack")
#include<bits/stdc++.h>
#define int long long
#define ll long long
#define down cout<<'\n';
#define debug cout<<" cucuucucuuu",down
#define NHP ios_base::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define modwwe int t;cin>>t; while(t--)
#define bit(i,j) (i>>j&1)
#define sobit(a) __builtin_popcountll(a)
#define task "test"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".ans","w",stdout)
#define pb push_back
#define mask(k) (1<<k)
#define checktime cerr << (double)clock() / CLOCKS_PER_SEC * 1000 << " ms";
using namespace std;
void phongbeo();
const int inf = 1e14;
const int mod2 = 1e9 + 7;
const int mod1 = 998244353;
const ll base=67;
int add(int x,int y)
{
if(x+y>=mod2) x-=mod2;
if(x+y<0) x+=mod2;
return x+y;
}
struct icd
{
long double a;
int b;
};
struct ib
{
int a;
int b;
};
struct ic
{
int a, b, c;
};
struct id
{
int a, b, c, d;
};
struct ie
{
int a, b, c, d, e;
};
ll n, m, s1, s2, s4, s3, sf, k, s5, s6, mx, s7, s8, s9, mx2, res, dem2 = 0, dem = 0, s33, dem3, dem4, mid, l2, r2, center;
int i, s10, s12,k1,k2,k3,s11,t,lim,w,l,r;
int kk;
int el = 19;
main()
{
if(fopen(task".inp","r"))
{
fin(task);
// fou(task);
}
NHP
/// cin>>s1;
// modwwe
phongbeo(),down
// checktime
}
int in[61];
int ou[61];
vector<int> v[61];
int a[16];
int b[16];
int f[61];
int par[61];
void dfs(int x,int y)
{
in[x]=++dem;
par[x]=y;
for(auto f:v[x])
if(f!=y)
dfs(f,x);
ou[x]=dem;
}
bool check(int x,int y)
{
if(in[x]<=in[y]&&in[y]<=ou[x]) return 1;
return 0;
}
struct dsconcu
{
ib dsu[61];
void rest()
{
for(int i=1; i<=n; i++)
dsu[i]= {1,i};
dem=n-1;
}
int get(int x)
{
if(dsu[x].b!=x)return dsu[x].b=get(dsu[x].b);
return x;
}
void noi(int x,int y)
{
if(x==0||y==0) return;
x=get(x);
y=get(y);
if(x==y) return;
dem--;
if(dsu[x].a<dsu[y].a) swap(x,y);
dsu[x].a+=dsu[y].a;
dsu[y].b=x;
}
}ds;
void skibidi(int x,int y)
{
s4=0;
while(!check(x,y))
{
s4=x;
if(!check(par[x],y))
ds.noi(x,par[x]);
x=par[x];
}
s5=0;
while(y!=x)
{
s5=y;
if(par[y]!=x)
ds.noi(y,par[y]);
y=par[y];
}
ds.noi(s4,s5);
}
void phongbeo()
{
cin>>n>>m>>k;
f[0]=1;
for(int i=1; i<=n; i++)
f[i]=f[i-1]*k%mod2;
for(int i=1; i<n; i++)
cin>>l>>r,v[l].pb(r),v[r].pb(l);
dfs(1,0);
for(int i=1; i<=m; i++)
cin>>a[i]>>b[i];
s6=0;
for(int i=0;i<(1<<m);i++)
{
ds.rest();
for(int j=0;j<m;j++)
if(bit(i,j))
{
skibidi(a[j+1],b[j+1]);
}
int total=1;
if(sobit(i)%2==1)total=-1;
s6=add(s6,f[dem]*total);
}
cout<<s6;
}
