#include "bits/stdc++.h"
#define int long  long
#define dick vector<int>
#define full(a) a.begin(), a.end()
using namespace std;

using vi = vector<int>;
using vvi = vector<vi>;
using pii = pair<int, int>;
#define V vector
#define Vi = V<int>
#define all(a) a.begin(), a.end()
#define forn(i, n) for(int i=0; i<n; i++)

double dist(int x, int y) {
    return sqrt(x*x*1.0 + y*y + 0.0);
}
double dist2(double x, double y) {
    return x*x*1.0 + y*y + 0.0;
}

void solveA() {
    vector<pair<int, int>> a(3);
    for(int i = 0; i<3; i++) {
        cin>>a[i].first>>a[i].second;
    }

    double mn = INT_MAX, mi = -1;
    for(int i = 0; i<3; i++) {
        pii other1 = a[(i+1) % 3];
        pii other2= a[(i+2) % 3];
        if(dist(other1.first - a[i].first, other2.second - a[i].second) < mn) {
            mn = dist(other1.first - a[i].first, other2.second - a[i].second);
            mi = i;
        }
        if(dist(other2.first - a[i].first, other1.second - a[i].second) < mn) {
            mn = dist(other2.first - a[i].first, other1.second - a[i].second);
            mi = i;
        }
    }

    cout<<fixed<<setprecision(6)<<mn<<endl;
}

double dotP(double x1, double y1, double x2, double y2) {
    return x1*x2+y1*y2;
}

void solveA1() {
    vector<pair<int, int>> a(3);
    for(int i = 0; i<3; i++) {
        cin>>a[i].first>>a[i].second;
    }

    double mn = INT_MAX, mi = -1;
    int precision = 10000;
    for(int i = -100 * precision; i <= 100*precision; i++) {
        for(int j = -100 * precision; i<= 100 * precision; i++) {
            double x = i*1.0/precision;
            double y = j*1.0/precision;
            for(int i = 0; i<3; i++) {
                pii other1 = a[(i+1) % 3];
                pii other2= a[(i+2) % 3];
                if(dotP(other1.first - x, other1.second - y, other2.first - x, other2.second - y) != 0) continue;
                if(dist2(x - a[i].first, y - a[i].second) < mn) {
                    mn = dist2(x - a[i].first, y - a[i].second);
                    mi = i;
                }
            }
        }
    }

    cout<<sqrt(mn)<<endl;
}

void mv (){
    int n, q;
    cin>>n>>q;
    dick a(n);
    for(int i =0 ;i < n ;i ++){
        cin>>a[i];
    }
    dick b(n);
    dick c(n);
    for(int i = 1;i < n ;i ++){
        if( a[i] < a[i-1] )b[i]  =-1;
    }
    for(int i = 1 ;i < n;i++){
        c[i] = c[i- 1] + b[i];
    }
    while(q--){
        int r, l;
        cin>>r>> l;
        r--;l --;
        if(c[r] - c[l] != 0 ){
            cout<< "NO\n";
        }
        else cout<< "YES\n";
    }
    return;
}

void solveS() {
    int n; cin >> n;
    array<int, 65> bs = {0};
    forn(i, n) {
        int a; cin >> a;
        for(int j=0; a; j++, a/=2) {
            bs[j] += a&1;
        }
    }
    unsigned long long res = 0;
    for(int j=0; j<64; j++) {
        if(bs[j]) {
            res |= ((unsigned long long)1) << j;
        }
        bs[j+1] += bs[j] / 2;
    }
    cout << res;
}
void trains () {
    int n , m, t;
    cin>>n>>m>>t;
    for(int k =0 ;k < m ;k ++){
        int p , s,  l;
        string d;
        cin>>p>>s>>d>>l;
        int dist = t * s;
        int st, ed ;
        if(d == "R"){
            st= p + dist;
            ed = st +  l - 1; //
            if( st < ed)swap(st, ed);
        }
        else {
            st= p -dist;
            ed = st + l -1 ;
        }
        string res(n, '=');
        for(int  i= 0 ;i < n ;i ++){
            if(i == st ){
                res[i] = '!';
            }
            else if ( i >= min ( st, ed) && i <= max(st, ed)){
                res[i] = '#';
            }
            else res[i] = '=';
        }
        cout<< res << '\n';

    }

    return ;
}


int xin() {
    int n; cin>>n;
    return n;
}
using vvpii=vector<vector<pair<int, int>>>;
#define pb push_back


int timer = 0;

using vb=vector<bool>;
void dfs(int n, vvpii& g, int v, int c1, int c2, vi& used, int p = -1) {
    used[v] = ++timer;
    for(auto& to : g[v]) {
        if(to.first == p) continue;
        if(used[to.first] && used[to.first] < used[v]) {
            if(c1 + (to.second == 0) == 0 && c2 + (to.second == 1) == 0) { continue; }
            if(c1 + (to.second == 0) >= 2 && c2 + (to.second == 1) >= 2) { continue; }
            cout<<"NO"<<endl;
            exit(0);
        }
        if(!used[to.first]) dfs(n, g, to.first, c1 + (to.second == 0), c2 + (to.second == 1), used, v);
    }
}

void nightmare() {
    int n=xin(), m=xin();
    vvpii g(n+1);
    for(int i=0; i<m; i++) {
        int a=xin()+1, b=xin()+1, c=xin();
        g[a].pb({b, c});
        g[b].pb({a, c});
    }
    vi used(n+1, 0);
    for(int i = 1; i<=n; i++ ) {
        if(!used[i]) dfs(n, g, i, 0, 0, used);
    }
    cout<<"YES"<<endl;
}


signed main() {
    nightmare();
//    solveA1();
    return 0;
}