#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxn 150

using namespace std;

int tt,n,m,s,t,v,fath[maxn],dis[maxn],flag=;

int getfather(int x)

{

    if (fath[x]==x) return x;

    int ret=getfather(fath[x]);

    dis[x]+=dis[fath[x]];

    fath[x]=ret;

    return ret;

}

void unionn()

{

    if (!flag) return;

    int f1=getfather(s),f2=getfather(t+);

    if (f1==f2)

    {

        if (dis[t+]-dis[s]!=v) flag=;

    }

    else

    {

        fath[f2]=f1;

        dis[f2]=v+dis[s]-dis[t+];

    }

    return;

}

void work()

{

    flag=;

    scanf("%d%d",&n,&m);

    for (int i=;i<=n+;i++)

    {

        fath[i]=i;

        dis[i]=;

    }

    for (int i=;i<=m;i++)

    {

        scanf("%d%d%d",&s,&t,&v);

        unionn();

    }

    if (flag) printf("true\n");

    else printf("false\n");

}

int main()

{

    scanf("%d",&tt);

    for (int i=;i<=tt;i++)

        work();

    return ;

}