#include<bits/stdc++.h>
using namespace std;
vector<pair<long long,long long> >vec[200005];
long long n,m,x,y,z,dis[200005],in[200050],op,t;
bool vis[200005];
void spfa(long long s){
	queue<long long> q;
	memset(dis,0xcf,sizeof(dis));
	memset(vis,0,sizeof(vis));
	memset(in,0,sizeof(in));
	dis[s]=0;
	q.push(s);
	while(!q.empty()){
		long long u=q.front();
		q.pop();
		vis[u]=0;
		for(int j = 0 ; j < vec[u].size() ; j++){
			long long to=vec[u][j].first,value=vec[u][j].second;
			if(dis[u]+value>dis[to]){
				dis[to]=dis[u]+value;
				if(!vis[to]){
					q.push(to);
					vis[to]=1;
					in[to]++;
					if(in[to]>n){
						cout<<"false\n";
						return ;
					}
				}
				
			}
		}
	}
	cout<<"true\n";
	return ;
}
int main(){
	ios::sync_with_stdio(0);
	cin>>t;
	while(t--){
		cin>>n>>m;
		for(int i = 0 ; i <= n+1 ; i++) vec[i].clear();
		for(int i = 1 ; i <= m ; i++){
			cin>>x>>y>>z;
			vec[y].push_back(make_pair(x-1,-y));
			vec[x-1].push_back(make_pair(y,z));
		}
		for(int i = 0 ; i <= n ; i++){
			vec[n+1].push_back(make_pair(i,0));
		}
		spfa(n+1);
	}
	return 0;
}

		vec[y].push_back(make_pair(x-1,-y));
		vec[x-1].push_back(make_pair(y,z));
	}
	for(int i = 0 ; i <= n ; i++){
		vec[n+1].push_back(make_pair(i,0));
	}
	spfa(n+1);
}
return 0;

}