#include<bits/stdc++.h>

using namespace std;

using ll = long long;

ll f[105], d[105];

ll fd(ll x) {
    if (f[x] == x) return x;
    ll rt = fd(f[x]);
    d[x] += d[f[x]];
    return f[x] = rt;
}

void slv() {
    ll n, m;
    cin >> n >> m;
    for (int i = 0; i <= n; i++) {
        f[i] = i;
        d[i] = 0;
    }
    bool ok = 1;
    for (int i = 0; i < m; i++) {
        ll s, t, v;
        cin >> s >> t >> v;
        ll p1 = fd(s - 1);
        ll p2 = fd(t);
        if (p1 != p2) {
            f[p2] = p1;
            d[p2] = d[s - 1] + v - d[t];
        } else {
            if (d[t] - d[s - 1] != v) ok = 0;
        }
    }
    if (ok) cout << "true" << endl;
    else cout << "false" << endl;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int w;
    cin >> w;
    while (w--) {
        slv();
    }
    return 0;
}