本地能过大样例，跟题解对拍很多组也没有问题

#include<bits/stdc++.h>
#define int long long
#define maxn 200005
#define multicase() int t;cin>>t;while(t--)
using namespace std;
const int mod = 1e9 + 7;
int n,m,v;
map<int,int> a;
vector<int> b;
int ksm(int x,int y)
{
	int res = 1;
	while(y)
	{
		if(y&1) (res *= x) %= mod;
		y>>= 1;
		(x *= x) %= mod;
	}
	return res;
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	multicase()
	{
		a.clear();
		b.clear();
		cin >> n >> m >> v;
		bool flag = 0;
		for(int i=1;i<=m;i++){
			int x,y;
			cin >> x >> y;
			if(a[x]) 
			{
				if(a[x] != y) flag = 1;
			}
			else a[x] = y,b.push_back(x);
		}
		if(flag)
		{
			cout << 0 << "\n";
			continue;
		}
		sort(b.begin(),b.end());
		bool noval = 1;
		int lst = 1,ans = 1;
		if(b.empty())
		{
			ans = ksm(v,2*n-2);
			ans %= mod;
			cout << ans << "\n";
			continue;
		}
		ans = ksm(v,2*(b[0]-1)) * ksm(v,2*(n-b[b.size()-1]));
		ans %= mod;
		for(int i=1;i<b.size();i++)
		{
//			cout << "i = " << i << "\n";
			ans *= ((ksm(v,2*(b[i]-b[i-1])) - ksm(v,(b[i]-b[i-1])) + ksm(v,(b[i]-b[i-1]-1))))%mod;
			ans %= mod;
		}
		ans %= mod;
		cout << ans << "\n";
	}
	return 0;
}