def spfa():
    dist = [0]*(n+1)    # ！！！注意：这里绝对不同用float("inf"),因为在比较dist距离时，dist[t]+w还是==float("inf")，因此不能更新距离
    st = [False]*(n+1)
    cnt = [0]*(n+1)

    dist[1] = 0
    queue = []
    for i in range(1,n+1):
        queue.append(i)
        st[i] = True

    while queue:
        t = queue.pop()    # ！注意：与求1号点到n号点的出队顺序不同，因为判负环要分别从所有节点开始判断，所以元素pop的顺序对结果不产生影响；所以优先用O(1)复杂度的pop()
        st[t] = False

        if t not in graph: continue
        for weight, node in graph[t]:
            if dist[node]>dist[t]+weight:
                dist[node] = dist[t]+weight
                cnt[node] = cnt[t]+1
                if cnt[node]>=n: return True
                if not st[node]:
                    queue.append(node)
                    st[node] = True
    return False

if __name__=="__main__":
    n, m = map(int, input().split())

    graph = {}
    for i in range(m):
        x, y, z = map(int, input().split())
        if x not in graph:
            graph[x] = [(z, y)]
        else:
            graph[x].append((z, y))
    res = spfa()
    # print(res)
    print("Yes") if res else print("No")