alg2025/src/8/11/P11362.cpp

#include <iostream>
#include <map>

using ll = long long;
using namespace std;
const int MOD = 1e9 + 7;

ll p(ll b, ll e) {
    ll res = 1;
    b %= MOD;
    while (e > 0) {
        if (e % 2 == 1) res = (res * b) % MOD;
        b = (b * b) % MOD;
        e /= 2;
    }
    return res;
}

void solve() {
    ll n;
    int m;
    ll v;
    cin >> n >> m >> v;
    map<int, int> mc;
    for (int i = 0; i < m; ++i) {
        int c, d;
        cin >> c >> d;
        if (mc.count(c) && mc[c] != d) {
            for (int j = i + 1; j < m; ++j) cin >> c >> d;
            cout << 0 << endl;
            return;
        }
        mc[c] = d;
    }
    if (m == 0) {
        if (n == 1) { 
            cout << 1 << endl;
        } else {
            cout << p(v, (n - 1) * 2) << endl;
        }
        return;
    }
    ll tot = 1;
    ll vmod = v % MOD;
    int lp = 0;
    for (auto const& [idx, val] : mc) {
        ll len = idx - lp;
        if (len > 0) {
            ll s;
            if (lp == 0) {
                s = p(vmod, (len - 1) * 2);
            } else {
                ll v2len = p(vmod, len * 2);
                ll vlen = p(vmod, len);
                ll vlenm1 = p(vmod, len - 1);
                s = (v2len - vlen + vlenm1 + MOD) % MOD;
            }
            tot = (tot * s) % MOD;
        }
        lp = idx;
    }

    
    if (lp < n) {
        ll len = n - lp;
        
        
        ll s = p(vmod, len * 2);
        tot = (tot * s) % MOD;
    }

    cout << tot << endl;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(nullptr);
    int t;
    cin >> t;
    while (t--) {
        solve();
    }
}