#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

using namespace std;

const int N=1e6+;

typedef long long ll;

inline int read(){

    char c=getchar();int x=,f=;

    while(c<''||c>''){if(c=='-')f=-;c=getchar();}

    while(c>=''&&c<=''){x=x*+c-'';c=getchar();}

    return x*f;

}

int n, m, l, r, v;

int fa[N], val[N];

int find(int x) {

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

    int root = find(fa[x]);

    val[x] += val[fa[x]];

    return fa[x] = root;

}

int main() {

    freopen("in", "r", stdin);

    int T=read();

    while(T--) {

        n=read()+; m=read();

        for(int i=; i<=n; i++) fa[i]=i, val[i]=;

        int flag=;

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

            l=read(); r=read()+; v=read();

            if(!flag) continue;

            int x = find(l), y = find(r); //printf("hi %d %d  %d %d  %d %d\n", l,r,x,y,val[l],val[r]);

            if(x == y) {

                if(val[r] - val[l] != v) flag = ;

            } else fa[y] = x, val[y] = v - val[r] + val[l];

        }

        puts(flag ? "true" : "false");

    }

}