'''
SPFA算法，解带负权边的有向图和不带负权边的无向图的单源
最短路问题
'''
from collections import deque

class SPFA:

    # start_node 为起始点，edges是边的三元组(节点1， 节点2， 边权重) is_directed表示是否是有向图
    def __init__(self, edges, is_directed, max_node_num):
        self.edges = edges[::]
        self.is_directed = is_directed
        self.max_node_num = max_node_num

    # 获取最短路径长度的列表[(节点1，长度1), (节点2, 长度2) .....]
    def getMinPathLen(self):
        return self.getMinInfo()

    def getMinInfo(self):
        link = {}
        dis = [0x7fffffff] * (self.max_node_num+1)

        for a, b, w in self.edges:
            if not self.is_directed:
                # 无向图检查是否有负边
                if w < 0:
                    return None

                if a not in link:
                    link[a] = []
                if b not in link:
                    link[b] = []

                link[a].append((b, w))
                link[b].append((a, w))

            else:
                if a not in link:
                    link[a] = []
                link[a].append((b, w))


        updated_nodes = deque()
        for i in range(1, self.max_node_num+1):
            updated_nodes.append(i)
        in_que = [1] * (self.max_node_num + 1)


        # 进行V次迭代，第V次检查是否是无解情况
        iter_times = 0
        while iter_times < self.max_node_num:
            update_flag = False

            # 利用上一轮迭代距离变小的点进行松弛操作
            node_num = len(updated_nodes)
            for _ in range(node_num):
                a = updated_nodes.popleft()
                in_que[a] = 0
                if a not in link:
                    continue

                for b, w in link[a]:
                    new_dis = 0x7fffffff if dis[a] == 0x7fffffff else dis[a] + w
                    if new_dis < dis[b]:
                        dis[b] = new_dis
                        update_flag = True

                        if in_que[b] == 0:
                            in_que[b] = 1
                            updated_nodes.append(b)

            iter_times += 1

            if iter_times == self.max_node_num:
                if update_flag:
                    return None

            if not update_flag:
                break

        return [[node, dis[node]] for node in range(1, self.max_node_num+1)]



n, m = map(int, input().split())
edges = {}
for _ in range(m):
    a, b, w = map(int, input().split())
    if (a, b) not in edges:
        edges[(a, b)] = w
    else:
        edges[(a, b)] = min(edges[(a, b)], w)

edges = [(a, b, w) for (a, b), w in edges.items()]

flag = False
algo = SPFA(edges, is_directed=True, max_node_num = n)
ans = algo.getMinPathLen()
if ans is None:
    flag = True

print('Yes' if flag else 'No')