import java.io.*;
import java.util.Arrays;

class Main {

    static final int INF = 0x3fffffff;

    static int n, m;
    //稀疏图，邻接表存储
    static int idx;
    static int[] h = new int[2100];
    static int[] e = new int[10010];
    static int[] ne = new int[10010];
    static int[] w = new int[10010];

    //spfa队列
    //由于会多次入队，长度设为n*m
    static int[] queue = new int[21000000];
    static int head, tail;
    static boolean[] isIn = new boolean[2100];

    //用于记录从某点到另一点的最短路经过的边数
    static int[] cnt = new int[2100];
    //存储两点间的最短路
    static int[] dist = new int[2100];

    static {
        Arrays.fill(h, -1);
    }

    static void insert(int a, int b, int v) {
        e[idx] = b;
        w[idx] = v;
        ne[idx] = h[a];
        h[a] = idx++;
    }

    static boolean spfa() {
        //全部顶点入队
        for (int i = 1; i <= n; i++) {
            queue[tail++] = i;
            isIn[i] = true;
        }
        while (head < tail) {
            int t = queue[head++];
            isIn[t] = false;
            for (int i = h[t]; i != -1; i = ne[i]) {
                int a = e[i];
                if (dist[a] > dist[t] + w[i]) {
                    dist[a] = dist[t] + w[i];
                    cnt[a] = cnt[t] + 1;
                    if (cnt[a] == n) return false;
                    if (!isIn[a]) {
                        queue[tail++] = a;
                        isIn[a] = true;
                    }
                }
            }
        }
        return true;
    }

    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        BufferedReader in = new BufferedReader(isr);
        String[] strs = in.readLine().split(" ");
        n = Integer.parseInt(strs[0]);
        m = Integer.parseInt(strs[1]);
        for (int i = 0; i < m; i++) {
            strs = in.readLine().split(" ");
            int a = Integer.parseInt(strs[0]);
            int b = Integer.parseInt(strs[1]);
            int v = Integer.parseInt(strs[2]);
            insert(a, b, v);
        }

        in.close();
        isr.close();

        OutputStreamWriter osw = new OutputStreamWriter(System.out);
        BufferedWriter out = new BufferedWriter(osw);

        if (spfa()) out.write("No");
        else out.write("Yes");

        out.flush();
        out.close();
        osw.close();
    }
}