// bzoj1202#include<algorithm>#include<iostream>#include<cstdlib>#include<cstring>#include<cstdio>#include<cmath>#define LL long long#define inf 2147483640#define Pi 3.1415926535898#define free(a) freopen(a".in","r",stdin),freopen(a".out","w",stdout);using namespace std;int fa[10010],m,n,T,r[10010];int find(int x) {    if (x==fa[x]) return x;    int f=find(fa[x]);    r[x]=r[x]+r[fa[x]];    fa[x]=f;    return f;}bool Union(int x,int y,int w) {    int r1=find(x),r2=find(y);    if (r1==r2) {        if (w!=r[y]-r[x]) return 1;}    else {        fa[r2]=r1;        r[r2]=w+r[x]-r[y];    }    return 0;}int main() {    scanf("%d",&T);    while (T--) {        bool flag=1;        scanf("%d%d",&n,&m);        for (int i=0;i<=n;i++) fa[i]=i,r[i]=0;        while (m--) {            int x,y,w;            scanf("%d%d%d",&x,&y,&w);            x--;            if (Union(x,y,w)) {flag=0;break;}        }        if (flag) printf("true\n");        else printf("false\n");    }    return 0;}