import sys
from collections import deque

n, m = [int(x) for x in input().split(" ")]

edges = []
for i in range(n):
    edges.append([])

for _ in range(m):
    a, b, barva = [int(x) for x in input().split(" ")]
    edges[a].append((b, barva))
    edges[b].append((a, barva))

skore = []
for _ in range(n):
    skore.append((0, 0))

zpetneHrany = []
for _ in range(n):
    zpetneHrany.append([])

visited = [False] * n

initnode = 0
stack = deque()
stack.append((initnode, None))



while len(stack) > 0:

    node, prev = stack.pop()
    if visited[node]:
        continue
    visited[node] = True
    # print(node)

    for nbr, clr in edges[node]:
        if not visited[nbr]:
            stack.append((nbr, node))
            if (clr == 0):
                skore[nbr] = (skore[node][0] + 1, skore[node][1])
            else:
                skore[nbr] = (skore[node][0], skore[node][1] + 1)
        elif nbr != prev and prev is not None:
            # zpetna hrana node do nbr
            # print(f"zpetna hrana z {node} dp {nbr}")
            zpetneHrany[node].append(nbr)

            barva = [0, 0]
            barva[clr] = 1

            pocet_c = skore[node][0] - skore[nbr][0] + barva[0]
            pocet_m = skore[node][1] - skore[nbr][1] + barva[1]

            if (pocet_c == 1 or pocet_m == 1):
                print("NO")
                sys.exit()
            pass

for odkud in range(n):
    for kam1 in zpetneHrany[odkud]:
        for kam2 in zpetneHrany[odkud]:
            if kam1 >= kam2:
                continue
            barva = []

            hrany = edges[odkud]
            for nbr, clr in hrany:
                if (nbr == kam1 or nbr == kam2):
                    barva[clr] += 1

            pocet_c = abs(skore[kam1][0] - skore[kam2][0]) + barva[0]
            pocet_m = abs(skore[kam1][1] - skore[kam2][1]) + barva[1]
            if (pocet_c == 1 or pocet_m == 1):
                print("NO")
                sys.exit()

    # print(node)

# print(skore)

print("YES")

# dfs_pole = [] # tuple[ jmeno, modra, cervena ]
# iin = [] # pozice i - in(i)
# out = [] # pozice i - out(i)
# stav = [] # 0 - nenalezeny 1 - otevreny 2 - uzavreny 3 - na stacku
#
# T = 0
#
# for _ in range(n):
#     stav.append(0)
#     iin.append(-1)
#     out.append(-1)
#
#
# def dfs():
#     global T
#     stack = []
#     stack.append(0)
#
#     while len(stack) != 0:
#         vrchol = stack[-1]
#         print(vrchol)
#         if (stav[vrchol] == 1):
#             vrchol = stack.pop()
#             stav[vrchol] = 2
#             T += 1
#             out[vrchol] = T
#             continue
#         stav[vrchol] = 1
#         T += 1
#         iin[vrchol] = T
#         hrany_v = edges[vrchol]
#         for soused in hrany_v:
#             if (stav[soused[0]] == 0):
#                 stack.append(soused[0])
#                 stav[soused[0]] = 3
#
# dfs()
#
# print(iin)
# print(out)